The original window regulators P/N 110072 and 110073 (commonly referred to as "Window Motors"), that came in the DeLorean were flimsy units. The split tubes can swell, the drive wheel can disengage from the cable, and the plastic mount for the tube can break. If the window switch is operated at either extreme of travel, the drive wheel can "chatter" as it skips against the stopped cable. The electric motor itself rarely fails, and is not available as a separate part from the regulator assembly.
If the unit seems to be "dead", it is often a failure of the Window Switch P/N 101177 itself. A good check for this condition (assuming the other side is still working) is to remove the ash tray and pop out the switches. Then reverse them left to right. If the problem follows the switch, replace them both.
The new replacements PN 110072 and 110073 have metal drive assemblies and better-braced tubes so that the old problems are eliminated. In appearance, the new units are plated yellow where the old ones are a silver color. An easy way to check is to remove the front amber door edge light and peer inside with a flashlight. The new units have colorful plastic protective tubes for the cable in the retracted position: red, blue, or black. The old ones were white.
The new regulators are installed and mounted differently than the originals, which often causes confusion when inexperienced installers perform this operation. Our replacement window regulators come with illustrated installation instructions. That said, the aftermarket units are so much more reliable and durable that once you go through the tedious ordeal of changing them, you will not have to do it again, ever.
Revised 7/5/2016 DAS [formatting, links]