1997 Buick Park Avenue Driver's power window problem

Just like every other Park Avenue from 97 - 02, the driver's power window in my car was not working properly. The motor works, but the door glass seemed to be binding up, and getting off track. I took out the window regulator, and took it to a repair shop near my house. I had the plastic sliders that go in the track replaced. The new ones came from GM, and I know are the correct ones. The old ones had to have the metal stem in the center ground off, and the new ones had the metal stem in the center welded in. They were well greased. I put it all back together, and same thing. I thought maybe the rubber channels that the glass runs in going up and down were not letting the glass slide along it well. I took them out and cleaned them as best as I could, and then armor-alled them. I put it all back together. It works somewhat better, but not the way it is supposed to. I don't know if there is something still wrong with the regulator, perhaps the pivot point in the middle has too much slack in it, or maybe the rubber channels that the window slides in need to be replaced? On previous GM cars, the glass had a clip that rode in the channel, on this car there are no clips. This car has probably been the worst GM car that I have owned. It drives real nice, but all these problems really add up. I see this same problem with the window on all the other Park Avenues from 97-02, so I hope someone here knows what needs to be done. If someone responds to my question, please have specific knowledge about this problem. Thanks.