96 E320 rear window went up and "POW" something broke. If this is like the old 300SD's then I know it's the plastic slider thingamagig. I've replaced those several times. But, I'm not sure about getting to it on these newer cars since I don't have a Haynes on it.

Is this a DIY project or should I let the Pro's do it?

It's a common problem, be careful with the door panel clips. Do a search, you will find detailed instructions and pics. I think you need a rivet gun to do this project. I didn't have one so I just paid $350 for a new regulator and motor.