85 528E driver's bottom power seat

I have an 85 BMW 528e. The power seats worked fine until a year ago. The drivers seat no longer moves up/down or back and forth. The back of the seat still moves but anything to do with the bottom part of the seat does not. The buttons still make a clicking sound when they are pressed but nothing happens. I switched the buttons with the passenger side to see if that was the problem but still nothing happened. Does anyone have any experience with this before?