Replaced the power window motors in my brother 02 Buick Park Avenue a few months back. While the motors were definitely old and needed replaced, the lift regulators were almost bone dry and the heavy windows were still overloading the new motors. After a good addition of some spray lithium grease on the rollers and channels, then exercising the lift regulators up and down, the windows were back to normal operation. Always a good idea to check your lift regulators and make sure they are properly lubed, otherwise you'll still end up putting a lot of stress on the motors and burning them up again.