My 1994 Mazda 626 has a chronic problem with the driver's side power window coming off the track and not closing properly (it goes down, but not all the way up) . . . I have had this problem "fixed" several times, but it always seems to come back . . . any suggestions, advice, etc.?

What has been checked up to this point? Here are some suggestions. You will have to take the door paneling off to check these. With the paneling off operate the window to see whats happening while its being opened/shut, hopefully you will be able to pin point it based on this observation. If not check the following.Check the rollers on the windows to see if they are miss aligned or are warn badly. If they are in good shape take a look at the regulator (which is the track the window slides up/down on) to see if the tracks are bent or the regulator itself is bent or the mounting nut are loose allowing the window to come off the track.Lastly check the motor alignment itself for it may be pulling the window of the track.