Yet another power window question

2005 2 W/D Nismo King Cab. Driver's side window stuck in the down position. Electrical checks indicated everything was OK. Replaced the switch unit on a well intentioned mechanic's advice. $102 (very stupid of me).
Got additional help from an onlineservice and discovered this is a very common problem. I also downloaded a manual. I was able to get down to the sheet metal level, but still couldn't get to the window motor. I could see it was well rusted so I used a long tip to spray the motor with contact cleaner. Put it back together and it worked for 3 days then died again. Took it apart, and sprayed it with WD-40 this time. Again it worked for a couple of days then quit. Now it works partially, but makes some groaning and grinding noises.
After all that, my question is this: how do you get to the motor to clean it out properly. I've read many threads on several different sites, and the general consensus is that all it needs is a good cleaning with alcohol and Q-tips to make it work. The dealer charges around $350 to replace it.
Thanks in advance for any help,
Davis