Are the relays which are located behind the seat clicking when you try to raise and lower? If so there may be an internal problem with the motor itself. Bang on the motor housing and sometimes it starts working. If so then you're on the right track. Motor replacement would be next. This is what I had to do on my 93 vert.
I had the click and no action on my 90gt it was disconnected wires on the breaker under the dash.
I was able to rebuild my gassed motor, it was actually very simple and what they want for new ones is highway robbery.