Well, we found out what GM uses for window regulator cables. They are called a BOWDEN Cable. You can read about them here:
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They cost about $3.99 each pre-made at any bicycle shop. The thinnest ones are 1.5 mm and that is what is used in our electric window mechanisms.The motor is a capstan winch with two of these cables on the same capstan.
If you can tune a fishing reel then you can fix this.
Save big bucks!!
You may need to shorten a cable so buy some 1/16th inch end ferrules and a crimper or press tool. You will pay about a dime each (tops) for the ferrules - but they may try to whack you on the press. I made one from a steel expansion plug that fit into the jaws of a bird-beak vice-grip.