1994 Mercury Topaz Seat belt track and motor

I have a 1994 Mercury Topaz 2 door. The automatic seat belt on the driver side have stop working. How can I tell if the problem is in the plastic track that it runs on, or if, its the seat belt motor? I found out that Ford discontinue making the track about two months ago. I can locate a motor. But none of the dealers or junk yards seem to have the track. That is why it would help to know which is the problem, the track or the motor. Help!