Hello, I'm a newer technician. I've been tuning for awhile but I'm still learning how to do a lot of repairs. I've been having a problem with my own 1947 Acrosonic piano and can't seem to figure out what to do.
In the lower range, the hammer rail falls down so the hammers can't rest on it. The rest of the hammers on the piano rest on the rail. When playing a note in the low range, the hammer will fall below where it normally rests on the rail and then is unable to make it back up when trying to repeat the note. Years ago, I hired a technician to fix it. He tightened the una chorda pedal dowel to raise the hammer rest rail so the hammers fell back on it. This only worked temporarily though. It seems to fall down after time. It also seems that it needs to be raised so high that it affects the sound and play as if you were to have the una chorda pedal down half way at all times. This is because the rest of the rail is fine.
Last year, I learned how to re-pin jacks and hammer butts. I had repaired pianos that seemed to have the same problem as mine, as far as the hammers not going up, by either re-pinning or just stretching out the jack spring and adding some Protek to the jack flange. On my Acrosonic, the hammers all fall fine. I took the action out and the jacks all seem fine. I tried stretching the springs and adding protek just in case it helped but it made no difference. The problem seems to be the hammer rail dipping down too much on the lower end and I can't figure out what to do about it.Here's a picture if that helps
I also have another problem now. After I took the action out and put it back in, some of the dampers throughout the low and midrange aren't working. They all seem fine but just don't go down enough to mute the strings. I took the action out again just to look and see if I could see anything wrong. I couldn't and put it back in. Now more dampers aren't working but some that weren't working before are working better. I've experienced this problem before with other pianos and the problem was always that the action wasn't tight enough in. I've got this in as tight as I can though. Is there something I might be overlooking or a trick to getting the action in any tighter in these pianos?
Any advice will be very much appreciated. Thank you.