Stereo & Electronics - Confused about window motor problem

The windows will sometimes not go all the way up, not work for about 30 seconds, and then go up a little bit, then do the same thing. Happens going up or down, and on both windows, using both switches. Do I need to replace the motor, or is the regulator or relay going bad?

http://www.ls1tech.com/forums/general-maintenance-repairs/985288-window-motor.html

window motors man, mine went out last winter kinda trick to change but lots of good info on the site for changing them out yourself.