Tuned a rental Yamaha C3 today for a Friday event, August 3, 2012. Here is a pic of what I found. Any guesses as to purpose? Later entry: Just realized that couldn't have been gum, or it would have been hardened. The substance was more like silly putty. I did lift off one piece, definitely pliable, then put it back in its original place. This C3 was a very nice instrument, less than 10 years old. #2012