I understand it's some kind of cable mish-mash in there. And they break or come off the pulleys. I bought a 100K warranty with our F150. The driver's window has been fixed 3 times already. I think I made money on the warranty.
1967 Falcon 4 door 351C-4V
1970 Mustang 351C-2V
http://raceabilene.com/kelly/hotrod
Owner built, owner abused.
