My drivers mirror won't move in and out but moves up and down ok,Ihave power mirror.This is on a 2000 F150, how can i fix the problem?

 

This could be either of two things, First,Id pull the switch,and clean it out,if that doesent work,you have a problem in the motor/gearbox assy in the mirror itself.
When pushing the mirror button in any direction,have someone stick their ear on it,it should "hum" while in operation,up/dowm-l/r. If it doesent hum l/r id say its a swicth problem...

 

Mine does that the gears are stripped if you put your finger on the top or bottom(slight presure)depending which way you want it to go it should work til you can find a new one