The motors themselves are usually fine; what happens is a plastic gear in the drive gets old and brittle and breaks. It's an easy fix & you can get brass gears from most Pantera Venders to fix them permanently.
Here's a nice write up: http://www.panteraplace.com/page59.htm
Or you can upgrade them if you like: http://www.panteraplace.com/page164.htm
PANTERA INTERNATIONAL
A DE TOMASO CAR CLUB
Presents the De Tomaso Forums
The On-Line Meeting Place for De Tomaso Owners and Enthusiasts From Around the World
Clicking on the banner will take you to the sponsor's website.