Wurlitzer clank Sound- F21

[pianotuner steveo]

I have a Wurlitzer that I am fixing up and there is that "clank" noise on the F below middle C. I know this has been discussed before, I think someone found the cause of this noise. I've heard it on several Wurlitzers.....

It's almost the same sound as if you try to play a note when a reed is loosened, but that is not the problem.
It's possible I may even have helped find the cause of this noise in the past, but I can't for the life of me remember what causes it.

This noise happens all the time, but is more noticeable when the amp is off.

Any help would be appreciated!

[pianotuner steveo]

I just found the old thread by searching F21...

I guess this happens on nearly every Wurlitzer.

Will see if slight adjustment on reed bar helps later today.

[DocWurly]

Adjusting reed bar won't fix it.

And yes, it's very common in the range F-21 to just below Middle C.  As high as that Bb or B.

[pianotuner steveo]

Any ideas on how to get rid of it?
My 206A does it too.

[Fred]

It is the solder slightly separating from the reed that causes this, usually at the edge of the pyramid closest to the fixed end of the reed. My belief is that the footprint of the solder counterweight is so large that it encroaches on a part of the reed that flexes under heavy blows.
To remedy this, remove the solder completely. File the end of the reed in the shape of the footprint for the solder pyramid. Tin the footprint, then rebuild your pyramid.

[pianotuner steveo]

Thank you, Fred, I will check that.

But why does it almost always happen on this one key? I know sometimes it's the E next to it, or other keys, but I currently am hearing it on a 200A and a 206A on the same note, and have heard it in other pianos in the past on the same note.. Coincidence?

[Fred]

I believe it has to do with the relatively large footprint of the solder pyramid, necessary for bringing the lowest of the #3 reeds down to the proper pitch. The F in question requires the largest counterweight, and in my experience, is most prone to this problem (the adjacent F# being a close second).
We know that upon being struck, a reed is bending in the shape of an arc. If adhesion of the solder is lost toward the fixed end of the reed, it suggests that a portion of the solder counterweight is located on a portion of the reed that exhibits some bending upon heavy blows. A slightly shorter, slightly taller pyramid may help reduce the chances of the problem reemerging. 

[pianotuner steveo]

Wow, Fred,  it worked. This is a real good tip to post here!

Thank you!

[Fred]

You are welcome, Sir : )
Thank you for the update!