of gears may not seem significant at the time, but each time  this  occurs,  small  particles  of  the  gears  will  be ground  off  and  carried  with  the  lubricate  through  the transmission. These small metal particles may become embedded  in  the  soft  metal  used  in  synchronizers, reducing  the  frictional  quality  of  the  clutch.  At  the same  time,  these  particles  damage  the  bearings  and their  races  by  causing  pitting,  rough  movement,  and noise. Soon transmission failure will result. When this happens, you will have to remove the transmission and replace either damaged parts or the transmission unit. As  a  mechanic,  the  first  step  toward  repairing  a transmission is the diagnosis of the problem. To begin diagnosis,  gather  as  much  information  as  possible. Determine   in   which   gears   the   transmission   acts up—first, second, third, fourth, or in all forward gears when shifting. Does it happen at specific speeds? This information will assist you in determining which parts are  faulty.  Refer  to  a  diagnosis  chart  in  the  manu- facturer’s  service  manual  when  a  problem  is  difficult to  locate.  It  will  be  written  for  the  exact  type  of transmission. TROUBLESHOOTING  A  MANUAL  TRANSMISSION Problem Transmission noise in neutral Transmission noisy in gear Hard to shift Gears clash or grind when shifting Transmission sticks in gear Possible Cause Transmission not aligned with engine Bearings dry, badly worn, or broken Low oil level Gears worn, scuffed, or broken Countershaft badly worn Excessive end play of countershaft All causes noted above Main shaft rear bearing worn or broken Gear teeth worn Engine vibration damper defective Speedometer drive gears worn Clutch disc defective Gears loose on main shaft Clutch not releasing Sliding gear tight on shaft splines Shift linkage out of adjustment Main shaft splines distorted Synchronizer  damaged Sliding gear teeth damaged Clutch not releasing Synchronizer  defective Gears sticking on main shaft Clutch not releasing Detent balls stuck. Shift linkage out of adjustment Corrective Actions Realign Lubricate  or  replace Refill Replace Replace Replace Same as above Replace Replace Replace Replace Replace Replace worn parts Adjust Clean splines or replace shaft or gear Adjust Clean or replace Replace Replace Adjust Replace Free up gears or replace defective parts Adjust Free up the balls Adjust 4-22