I have a Custom 22 with Trem bridge. When I use the trem I get the dreaded ping, but at the bridge. Also when I tune the D string as I get to pitch I get the ping. I went over the bridge setup with the "fine-tooth comb". My service guy checked the nut slots, even polished them with a very fine grit "sandpaper". 8000 grit. This guitar plays wonderfully, stays in tune with no trem use. I suspect for some reason there is problem with the bridge plate that the string is held against. The ball end is "jumping" somehow. I have not dismantled the bridge. I also lubed the nut and saddles, no difference. One thing I noticed, the knot at the ball end sits right at the plate. Looking for ideas to solve this problem.