Wurlitzer 700 bass notes choking on hard strike

[AA]

Hi, I have a Wurlitzer 700 with the lowest few notes choking on a medium to hard strike, the note doesn't play except for a quiet harmonic. Weirdly the note works better if you press the middle of the key, this is only on white keys, the sharps in the affected section of keys work fine.
I'm wondering if anyone has experienced the same thing and knows what adjustment is needed.
I've had it for a few months, when I tested it at the guys house it all worked, then after a bumpy drive home I noticed the issue, just getting around to fixing it now as other than that issue it plays well already.
Thanks.

[pianotuner steveo]

It sounds like you need to adjust the Letoff so that the hammer releases from the Reed later , or possibly slightly sooner. It depends if the hammers are blocking against the reeds or not. The correct tool is sold on eBay with no minimum order amount. Common tools can not be used for this adjustment. I had the exact issue when I bought my 700 in the '70's (or it sounds like the same issue) This partially led me to become a piano tech. Don't bang on the keys- until it is repaired, that can lead to broken reeds.

[pianotuner steveo]

The other possibility is that the keys are pressing down too far. Check to see if the felt strip at the front of the white keys (under keys) became unglued and moved during transport. This model does not have individual round felts like later models and acoustic pianos.

[AA]

Hi thanks for the advice, I took it apart and more work has been done than I thought, new damper felts which I knew already, but key bushings have been replaced, and key weights have been added on top of the keys.
The important part is the felt strip for the white keys has been replaced with green felt round punchings so that dosent seem to be the issue.
I'll try and get the tool soon and hopefully that's all that's needed. with the case open it sounds like metal on metal clanking, it's not the reed bar otherwise I would hear a loud sound when it's on, but I think the reeds might be a bit loose, kind of stumped.
On another note it looks like i accidentally broke one of the solder connections to the volume pot, mine has the power switch moved to the back so it's not anything like that, but I just wanted to confirm that the volume control is set up with all 3 pins of the potentiometer used? I don't think the tech who worked on it would have left a wire running up if it wasn't needed as he did a really good job on the amp asides from the added effects loop being to hot for anything without an input/output volume control but I don't want to break anything by re soldering it so thought I'd ask. Thanks.

[AA]

Ok ignore the last part found a schematic and yes all 3 pins are used

[AA]

Ok I made an improvised tool out of hardwood dowel that only works for like 1 adjustment before becoming useless, but let off dose seem to be the problem.
I'll probably order the tool when vv gets it back in stock as I need some other stuff from them, shipping becomes too expensive for me when ordering from eBay since I'm in Canada. For now I guess Ill just keep cutting notches in dowels until I'm done, I have allot of them luckily.
Thanks.

[velo-hobo]

If you're in Canada but close enough to the border, could you have it shipped general delivery to a post office, or to a familiar store on the US side? I've sent small, relatively cheap parts to folks in Canada this way before, when it was convenient enough for them at least. Shipping is cheaper, faster, less hassle, and the items are more likely to actually make it to the destination....

[AA]

Thanks for the suggestion,
I do actually use a service pretty often that receives packages in ny and brings them close to me for a $5 CAD fee, I might end up going that way, it's not super expensive, I just don't like spending more than the actual product cost on shipping but that may be the way I have to go.
As for going over the border it's too much time for the money saved, from where I live.

[pianotuner steveo]

The letoff tool is available on eBay. No minimum order or $25 shipping like VV. Are you 100% sure that the white key key dip is not too deep in the problem area? If you press the key slowly, does the hammer just block against the Reed? In over 45 years, I've never seen loose reeds unless someone messed with yours that did not know what they were doing.

eBay has a U.S. shipping hub for international orders. It does not cost you extra like it would if item were shipped directly to you. eBay deals with any customs issues.

[AA]

There is at least 1/4 inch between the reed and hammer tip when I press slowly, what it looks like is the hammer is hitting the reed then muting it on the way back down. After looking at it a bunch I don't think the reeds are loose,
I'm guessing the sound I hear is somewhat like touch harmonics on guitar, or whatever you call it when you pluck a string with your finger over a fret and pull the finger away at the same time.
I took a slow motion video on my phone, it's not slow enough to fully see, but it dose look like it's hitting the reed, then bouncing back up almost enough to hit it again, causing the harmonic thing. I will also try adding some paper punchings to the front rail pins just to see if that helps.
https://youtube.com/shorts/EPRrhiMRRGU?si=vR1QQvPno3CvdvWL

[AA]

Here is what it sounds like, before turning the let off screw clockwise a little bit with my diy dowel tool it was consistently worse, now it doesn't always happen, but I feel like I have to play harder than I should to get the hammer to hit on the keys I adjusted.
https://youtube.com/shorts/7YJ7rt0ATh8?si=edFp4e_Tk_AE4ETW

[pianotuner steveo]

Ok, after watching both videos, it sounds/looks like those hammers are letting off way too early. You need the tool that's sold on eBay. One of your videos looks like it's slo mo, not sure if that was intentional. eBay does not charge you extra to ship from US to Canada as far as I know. They have a shipping hub in Illinois and items get sent to the respective countries from there.
This adjustment is very sensitive on the 120/700 action. Turn the screw just a little bit at a time,then test. It's been quite a while since I've adjusted a 700, but if I remember correctly, you want to turn the screw counterclockwise to improve. (in this instance) On the first test key, pick your worst one and try turning the screw about 1/4 turn at a time and see what that does.

[velo-hobo]

I've also come to understand that excessive let-off can create this sort of double strike. It seems counter-intuitive no doubt. Something to do with the effect it has on aftertouch?

I'd also suggest that it's important to check the entire regulation of the keys in question to be sure there aren't other factors making it more difficult to find a let-off adjustment that is acceptable. It's been a while since I touched a 700, but on the later pianos I work on, if something is messed up with the earlier steps of regulation, attempting to fix an issue only through let-off can become a fool's errand.

Caveat that I'm almost assuredly less experienced with mechanical aspects of piano tech work than Steve. I've been doing this type of work for well over a decade, but primarily as a hobby and occasional paid side gig for friends and acquaintances. I'm sure there's a lot more that I can learn about regulating a Wurlitzer. Part of why I still check in here regularly!

[pianotuner steveo]

Yes, Letoff and aftertouch go hand in hand. It is important to check hammer line and key dip too, especially since the way dip is achieved on this piano has been altered. Assuming dip is correct, Letoff is the next step, but it won't hurt anything to try to adjust Letoff on a couple of notes to see how different it feels. Tariffs and USPS rates going up have caused the price of the tool to increase, but it is well worth it to own the correct Letoff tool.
Also this action is more difficult to adjust than the 140/200/300 actions. I've never worked on a 112 action, but Letoff on the the 112A/120/700 action is tricky. (It's same action on these models)

[pianotuner steveo]

Be sure to check the dip in the problem area- are those keys pressing down too far? Not far enough? Just because someone put the individual front rail felts in, it does not mean that it was truly done correctly. If the dip is too shallow, it feels "choked" in your fingertips. If too deep, hammers can block against the reeds and break them also.

[pianotuner steveo]

I just found 2 different sellers on eBay that are selling a piano key dip block. One is only $2 plus shipping. You place the thicker end towards the front of the piano, and when you press the key down, the top of the block should be flush with the neighboring white keys that are not pressed down. This does not work for the black keys, only the whites. The 700 black keys have a screw in the keybed that you raise or lower to adjust dip. The bottom of the black keys have a piece of felt glued on so that they don't make noise when they hit this screw, if the black key gets buried below the neighboring white keys, the screw needs to be raised. (And/or the felt is missing)

[AA]

Ok thanks for the help, I'll try and get the let off tool as soon as possible, probably a keep dip block as well, altho I do have a 3d printer that's pretty precise and dose not get much use so I may see if I can just make something for key dip.
The key dip dose feel normal to me, but this is my only Wurlitzer, I've never played a different one, and I haven't touched an acoustic piano since primary school, so my only point of reference would be synths or Rhodes keybeds and that may be throwing off what feels normal to me.

[pianotuner steveo]

The key dip should be roughly the same on any properly regulated keyboard, including those which can't be regulated such as (most) digital pianos and keyboards. 3/8"-7/16" is normal. Most people use 3/8". I prefer 7/16" on heavier feeling actions such as many Rhodes. Deeper dip makes the action feel lighter,but the 700 action is very light so I would go with 3/8". Even if the key dip is too deep or shallow by 1/32" or 1/16" it can throw off the Letoff in this very sensitive action.

If you haven't done so, look up the 700 service manual (or 112A or 120, the actions are the same) and read and reread the action adjustment procedures.