Hello, and welcome to the forum. That is some really nice wood-work you've done there. I love my 54. It is probably the last thing in the world I would ever sell.
I am not an expert, at anything, but perhaps I can offer you a few suggestions.
1) I had the same issue with a couple of tines when I first got my 54, and the screwdriver test was the same result. I ended up replacing one of the tines, and got away with using a tone-bar clip on the other. Have you tried swapping the B with one of its neighbors to see if the problem follows the tine?
2) Are the keys grouped together, in a certain range, or just randomly scattered about? Usually when I've had a problem like that it's because the damper bar was not aligned properly into one of its sockets.
3) If your pickups are adjusted properly and are as close as possible to the end of the tines, you may have a dead pickup in there, perhaps where the volume begins to drop off significantly. The 54 pickups were originally wired in series, and unless you modified that by adding jumpers to make it series-parallel (groups of three in parallel, wired to the next group in series) I think that if you have one bad pickup you can either lose the whole piano, or just the pickups following the bad one. I know that there has been some debate around here about this, but I don't recall what the final answer was. If you're handy with a multi-meter, I would definitely start by checking the resistance across those pickups.
4) I wouldn't try bending the hammer head as you would risk breaking it and then you would be sad. If the hammer is not hitting the tine properly, it could be a multitude of things. Perhaps you could post a short video, that would help to see what is going on there.
I will offer one more suggestion; I was able to do a lot of the work you have done when I first got my 54. But I took it to a proper tech to have it tuned and voiced, and to address a few duff notes. I don't remember what it cost, but I do remember that it didn't seem like much when I considered the fact that he was able to dial in my piano in a couple of hours, whereas I would have probably spent days if not weeks on it, and in the end it may or may not have come out sounding as good as it does now.
I am not an expert, at anything, but perhaps I can offer you a few suggestions.
1) I had the same issue with a couple of tines when I first got my 54, and the screwdriver test was the same result. I ended up replacing one of the tines, and got away with using a tone-bar clip on the other. Have you tried swapping the B with one of its neighbors to see if the problem follows the tine?
2) Are the keys grouped together, in a certain range, or just randomly scattered about? Usually when I've had a problem like that it's because the damper bar was not aligned properly into one of its sockets.
3) If your pickups are adjusted properly and are as close as possible to the end of the tines, you may have a dead pickup in there, perhaps where the volume begins to drop off significantly. The 54 pickups were originally wired in series, and unless you modified that by adding jumpers to make it series-parallel (groups of three in parallel, wired to the next group in series) I think that if you have one bad pickup you can either lose the whole piano, or just the pickups following the bad one. I know that there has been some debate around here about this, but I don't recall what the final answer was. If you're handy with a multi-meter, I would definitely start by checking the resistance across those pickups.
4) I wouldn't try bending the hammer head as you would risk breaking it and then you would be sad. If the hammer is not hitting the tine properly, it could be a multitude of things. Perhaps you could post a short video, that would help to see what is going on there.
I will offer one more suggestion; I was able to do a lot of the work you have done when I first got my 54. But I took it to a proper tech to have it tuned and voiced, and to address a few duff notes. I don't remember what it cost, but I do remember that it didn't seem like much when I considered the fact that he was able to dial in my piano in a couple of hours, whereas I would have probably spent days if not weeks on it, and in the end it may or may not have come out sounding as good as it does now.