Jimbob, when the plastic thing breaks the motor runs the worm turns

but nothing moves, if the window is down it generally stays down and if it's up it often falls down. It's a virtual certainty your problem is nothing but the plastic part. I see you have a 2006 model. Go to
http://www.steigerperformance.com/products/sp13001.html and scroll down to the bottom of the page to the Wizard and Spotter Guide links for information on 2006 parts. There was a switch in design on the assembly line about 3/15/06 plus some folks who had a dealer warranty replacement done also got the later design. I'd strongly recommend you dig into the door to see what's actually broken before ordering a whole regulator assembly that IMHO you probably don't need.
It takes about 45 minutes per door to do the fix. The problem is so common that I just went ahead and did all 4 of mine before any failed. I would add a comment to the instructions. The instructions mention bending the ball stud shaft so it's parallel to the ground but are not totally clear on why. The why is so that the retention clip, you will see what I mean in the instructions, fits evenly behind the ball head; if it's not even the ball head can pop loose. Once the clip is installed tug on the part a few times to make sure it's secure and after you reach a point just before putting the water dam back on run the window up and down about 12 times to make sure everything stays together. I did not get the clip quite right on one window and, due to a lack of testing, the ball popped loose so I had to go back in
