It's a 1984 and runs splendidly now that carb problems have been partially resolved. Goes fast. But now the starting clutch plate seems to have gotten too thin or is just too slippery, so the bike is difficult to impossible to start. I suppose there's a way to get a new plate made, but is there any way of either resurfacing or shimming out the old clutch plate so that it'll work? I've sanded all clutch friction surfaces with fine sandpaper on a flat marble surface plate, but perhaps a coarser abrasive might work better. Any ideas?