i have to manually lock the doors but the unlock button unlocks them but they dont lock when i hit the lock buton i can hear hear the motor and see it push on the locks but they dont engange could it be the gearing or is the motor weakening??

 

My 89 does the exact same thing and it one of two things or a combination of both. Yes, the motor could be weekening, but more than likely you just need to lubricate all the moving parts real well. Get a can of white lithium grease, pull the door panals and hose down the guids, lock rods and everything thats part of the mechanism.