Control Box on 84 300 SD
 

I took my car into my mechanic because my driver-side wouldn't move in any way. He thought it was just the switch in the door, but called me later and said that he put in a new switch, but now thinks it's the control box under the driver's seat. A new one cost 900 bucks.:( I guess the good news is that no one else is going to be driving my car. He said this is the first time he has seen a control box go bad. I'm wondering if there aren't some relays or a way to test the resistors in the box. Basically I'm clueless on what to do.

Any ideas?

Help!