I've noticed a number of keyslips that bow (crown?) and/or tilt towards the key fronts, thus causing keys to stick down when played. Today I visited a YC TG150 baby with this problem.  I had pulled the action in it just over a month ago and all was well when I left that day. Today, I could hardly get the keyslip out (or back in), the ends were binding so tightly against the sides... much, MUCH harder than last month.  I've shimmed a couple of these out now with front rail felts which results in a nice even gap, but I curious why I'm seeing so many of these lately. At least 50% are on pianos that I either have not seen or at least not removed the keyslip in the past. The one I did two days ago had a folded up business card (current owner's mom's tuner's card from 20 years ago) already in there. I've only been tuning for about 3-1/2 years, and I see more pianos these days, but the incidence seems to be picking up noticeably. Is this such a common problem in general? I'm thinking that today's was possibly caused by increased humidity, except I believe there was a thread recently that mentioned that expansion isn't really an issue along the grain... and come to think of it, I don't believe that this keyslip is "wood" anyhow. Thoughts? Paul Bruesch Stillwater, MN