Since you're now into the repair fairly deeply, I strongly recommend the upgrade to Taurus window motors explained in other posts. This is not a difficult job to do and makes a world of difference in the windows. Having done it on my car, I wouldn't even consider trying to fix the old system.
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.