Some of you may recall, last Saturday I had a sostenuto problem with a performance Yamaha CFIII. The problem occurred if you engage the sostenuto pedal, then the damper pedal, and release the sostenuto with the damper pedal still down. The sostenuto rail became locked up until you finally release the damper pedal causing a loud slap. I received many excellent ideas from you and Kent even sent me a copy of his January article. Yesterday I was able to arrive early enough before the concert to diagnose in peace and quiet. The problem was that the sostenuto rail was positioned too far into the action cavity, so the blade had too much overlap. If you engage the damper pedal after the sostenuto is down, the blade could not rotate past the tabs when you release the sostenuto, because the blade is too close to the pivot points of the tabs. Thus the blade is locked up until you release the damper pedal. The loud slap was caused by two parts of the sostenuto pedal linkage suddenly coming back together. On this Yamaha, the in/out position is adjusted by bending each mounting bracket. After making the adjustments, the sostenuto worked perfectly, just like the textbook (or Kent's article). Now if you release the sostenuto with the damper pedal still down, you hear all the tabs immediately rub past the blade. But the noise is quite moderate on this piano. All the other tests worked perfectly. Nothing was on the edge of just working. Again, thank you for your help. I learned a lot. Jerry Cohen, RPT New Jersey Chapter
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