The one that got dropped onto concrete by my mom.
Turns out the focus ring was binding because of the way the filter frame bent. Busted the rest of the glass out of the filter and got the frame off with a pair of pliers. The lens now works (mostly) fine, front barrel is a tad loose though - more so than I remember.
At least I have a walkaround lens again, the 70-300 wouldn't cut it for that.
Goes to show how well it's built for being of a plastic construction, though. Five foot drop onto concrete with the camera attached, and both still work...