[rustytruck50]

If you have a caliper set or just a ruler, see if you can compare the size of the rollers....the front one may be worn just enough to jump out with the torque of the motor. If you haven't already done this, you could run the window up & down a few times with the door panel off and see if you can find anything out of the ordinary when the rollers move in the slides. I have seen too much grease on those nylon rollers be as bad as not enough...that grease has a real tendency of breaking down the nylon over the years.