I look after a Karl Muller G-175 (perhaps a Samick?) that is terrifically unstable in the mid section, though the bass and treble are pretty good. A well-maintained Piano Life Saver isn't helping much. This piano belongs to a teacher and I have to tune it every 8-10 weeks. All plate bolts are tight and there's no sign of plate damage or problems with the case.
The one thing I hadn't thought of was the plate flange to pinblock fitting. In the bass and high treble I can 't force a business card in between the block and flange, but in the centre sect ion the gap is .104"!
I seem to recall someone mentioning that maple shims can be forced into the gap and glued in to help solve that problem. Would that work? Where would I get the shims if it might as I'm not really a woodworker ? How many would I use ?
Another alternative someone suggested was to turn the piano upside down and fill the gap with epoxy. I n this case that isn't an option.
Does anyone have any suggestions?