This is some info I got from the Buick web site.
The window regulators go bad because of water getting past the waist seal. The water after some time (10-20 years) corrodes the window tray, the metal base the glass sits on.
Before starting any teardown, match mark everything you touch, and possible take some pictures for Identification. You need to remove horseshoe clip behind hand crank.
I removed the old sash channel, which was corroded and gave it to welder to attach the two brackets from original and placed on new. He was meticulous and specialized in antique cars. He ground off the excess welds. And I got the new channel plated, for additional corrosion protection. He did a fantastic job. I asked him for it to look good, even though it wouldn’t be seen.
I installed a new waist seal. Investigate seal installation before you buy. I got seal from Rubber Steele(No special Reason). You can also get seal from Metro Rubber.
I wouldn’t touch window crank coil spring, if it works, don’t mess with it. If it’s seized or hard to move, soak it over night in rust dissolver.
Worst case scenerio is that it will sound like Jack In the Box if you leave it with no lubrication. Make sure you lubricate coil spring after you remove rust.
Lubricate inside channel with grease. Spray lubricant at moving joints.
With window glass out you can clear drain passages at bottom of door, and blowout the trash.
Don’t loose the horsehoe shaped clip that goes behind the hand crank.