My D-string tuner was slipping, as though the tension of the string, when in tune, was too great, and causing the post the string was wrapped around to turn. I noticed that the tuning key turned really easy for about a quarter turn (around where the string was in tune) but that if I tuned a half-step sharp or flat, there seemed to be enough friction to keep the string at that pitch. So I found a new use for rosin -- thinking maybe there was just too much oil or something on the gear at that point, I rubbed rosin into it and worked the tuning key back and forth. I'm sure there's some reason not to do this, butI only had a few hours til the gig, and no time to get to a luthier. It seems to have done the trick! Just posting in case anyone has a similar problem in the future and does a search for a quick fix. I am not a luthier and for all I know this may do irreperable harm to your bass, but there you have it.