About 3 weeks ago i was summer first crusing and stopped engine for a while(10 min)i started riding again and gearbox was jammed.i found only 1st and 2nd gear and the selector was moving very slowly.I openend gearbox and only reason what i found was missing oil seal sleeve gear bearing.maybe one reason was that most of oil was gone but no any mechanicak damages.Now after over hauling i find only 4th gear and neutral!!!,any ideas what i did wrong-maybe something wrong in outer cover position...