window motor

I have a 94 325i conv, and both windows recently began intermittently malfunctioning when the doors open and close. They are supposed to go down around 1/2" or so I guess, and sometimes they work and sometimes not. Any suggestions? I want to hopefully fix w/o replacing as the dealer wanted $400 each for those parts

damp air and time equal corrosion.. clean connections and Most of the time your good to go. Worked on mine. Later Mark.