Complete instructions with photos:
from Ebay.com
The way that replace a window regulator in a 2003 Buick LeSabre front drive side is by removing the door panel. Next, disconnect the electrical connector on the regulator and replace.
Remove the door panel, (make sure that the regularor & motor is not bad), either jump the connectors to roll the window up or manually push the window up if the regulator is bad. If the regulator is bad, the window will slip back down. Regulator is $200 at the dealer and $200 for a new motor. Regulator & motor combined on Ebay is $90.
Take your door panel off and replace them...
See this post for instructions and photoshttp://www.ricksfreeautorepairadvice.com/repair-topics/window-power-repair/replace-a-power-window-regulator
Most likely it is the regulator, either the cable is broken or the plastic at the top broke and the cable became unspooled and wrapped around itself. The window is held in by two screws that tighten a clamp on the window that holds pretty tight so it is doubtful it is that.
You need a 3/8 drill bit to drill-out the rivets and then replace the motor that way. It might be easier to replace the whole regulator.
To put the power window of a 2003 Buick Rendezvous back on track, first, remove the door panel to access the window mechanism. Ensure that the window is in the fully closed position, then carefully realign it within the track by pushing it back into place. Check the window regulator and ensure that any clips or guides are securely attached. Finally, test the window's operation before reassembling the door panel.
Replace window regulator.
Because of a bad design on the window regulator. Bad nylon spindle that guides and spools the metal cable. The only way to fix this is to replace the regulator.
I have that car and you can remove them from the truck of the car.
I am assuming you are talking about a front door power windoe regulator, but the back door is similar. 1-Remove the interior trim panel. 2-Unbolt the two bolts or nuts or clips securing the glass to the regulator. 3-Slide the window to the two-thirds down position, tip it forward, then slide it up and out of the door. If this frightens you, instead slide it all the way up, and secure it in place with a lot of masking tape. Removing it completely is much safer. 4- Disconnect the electrical connector. 5-Unbolt the 4 bolts mountin the regulator to the door and if there are three more for the motor remove them also. 6-Maneuver the regulator out of the door. 7-Install the new unit by reversing this process.