My cars had low mileage, so the windows were not used all that much, but the little Blue plastic tube broke at the shoulder which then allowed the spring to push the tube up past the end of the cable shield which then loses all the cable tension.
My friend, Jim, made a replacement tube out of Aluminum which is much stronger than the plastic tube from Chevrolet.
My replacement aluminum rube must have the slot in order to slip it over the endless cable.
Burt after I slipped the Aluminum piece into place and slipped the cables back into the corner pulley sheaves, I still could not get adequate tension back into the endless cable. The cable seems to be routed correctly, but is still too loose. I don't know what to do.
Notice the Aluminum replacement tube in on the left. The other Blue plastic tube on the right has not broken and is still working fine.
