When I got my R-100 GSPD last summer (1993 with ~60k miles on her), the speedo needle bounced all over the place. Heisenberg would have appreciated it, because all it showed was a probability of my actual speed. While moving along with traffic on the interstate, it would fluctuate between 45 and 85 MPH, in a nice, rhythmic cadence. (Think of a cat watching a ping-pong game, but sped up about 3x.) I have never lubed the cable, or done much of anything with it. I took it out of its drive in the tranny to replace its cracked rubber boot, because I don't think I want any water going in there. I didn't see anything wrong with that end of the cable, so i just replaced the boot and put it back in. I cleaned and lubed lots of little parts on the bike, but never messed with the instrument cluster. The bouncy needle seemed like a minor annoyance, not worth a high position on the priority list. ...but I recently noticed it has healed itself. In fact, it's absolutely rock steady at all speeds! The bike had not spent long periods sitting. Previous owner put a couple thousand miles a year on her, as far as I can tell. The most logical conclusion I can come up with is that this machine is possessed, ala Christine. I hope the corroded battery cable fixes itself next, or maybe the scratched up valve covers. I want to say the tach was bouncy too, but I may be imagining that. In any case, it is currently very smooth.