I just bought a 1990 Sportster, with less than 10,000 miles, and sometimes the gear shift just doesn't want to go into the next gear when riding. Maybe once every twenty shifts, up or down, makes no difference. It feels like the lever has locked solid, but if I push it a second time, without moving the clutch or anything, it'll slip happily into gear. I pulled the primary cover (as I was looking to change my foot rests back to standard and some clown has cut the stud of level with the cover) and noticed several tiny chunks of metal in the bottom of the casing. Also some fine metal dust on the magnet. I've changed oil twice, adjusted the clutch twice, adjusted primary chain twice, still no difference, the gear shift refuses to shift on occasion. Any ideas? I'm running 20/50 engine oil in there at the moment, as it is all I had at the time, and I'm doing minimal miles on it until I get it sorted.