Clean and lube the door hinges several times as they need to ground, bad design. Or just run an extra ground cable from the door inner shell/power window motor mount through the rubber boot to the inside of the body behind kick panel. Then live wire to either side for up or down. Any issues after that are generally burnt out wiring and window switch due to the load and overheating. Rewiring with relays is eventually best, even on a good working system, the window motors are generally fairly bullet proof.