Thank you, Old Diesel for your reply. I have tried to remove the seat-back. There are two screws in the bottom. I have removed those, but I cannot see how to remove the seat-back. Yes - I know - it's easy, once you know how. Instructions please! Thanks!
Today I removed the seatback. Actually, I just had to move it down about 12 inches to expose the mechanism. It's easy once you have done it. I found that the rack had jumped out of the case that holds the pinion. That case is broken. The reason is, that the motor that drives the pinion does not stop. There is a switch attached to the motor that counts revolutions and turns the motor off before the rack reaches the end of the allowable travel. When the switch doesn't work, the motor doesn't stop and breaks things. When I get everything working I'll report back in.