The rear window on my '90 Blazer is becoming more and more sluggish as the years go by (for that matter, the two side windows on the doors are suffering from the same fate). When it finally goes, is there a better system out there, more modern motor, more modern regulator, etc? Or am I stuck with repairing the factory stuff? The window was never very efficient to begin with...my parents used to have an '87 full size Bronco, and the back window on that thing went up and down much better (so did the side windows). Is GM's system just simply less efficient? Any help would be appreciated. Thank you.