One of our esteemed colleagues does not directly participate on these lists (or any other lists for that matter), but benefits indirectly by having me consult all y'all on his behalf from time to time. Below is his description of the problem he is currently facing.
"A 1988 American Steinway B has stuck hammer flange centers and the flanges themselves are stuck, almost glued, to the black cloth on the hammer rail. The hammer rail cloth was definitely gooey. When I began repining, both ends of the extracted center pin were coated with a black, sticky substance from the bushings. I repined a total of 9 hammer centers. Most would swing one time or were completely frozen, several swung three times. The rest of the hammer centers were free. The problem presented itself as no or slow repetition.
The owner of this piano has a humidity control system (just a humidistat and the heater rods, since it is never too dry in her home) and a string cover. The piano stays in tune beautifully.
This piano was made after Lloyd Meyer left Steinway when they briefly used the Renner parts on B's and D's and went back to the American parts after Lloyd was gone. I believe they soaked the bushing cloth in some sort of liquid Teflon. Not sure and have no idea of the procedure. Protek did nothing. I needed to physically ream and burnish the bushings and install a half size larger (21) pin. I'm sure there will be more stuck centers."
I have not encountered this before. Have any of you?