Your problem is quite common on older Benzes. The teeth on the window regulator get chewed up from people holding down the button too long while rolling the window up. The motor is so strong it chews away the last couple of teeth resulting in a nasty rattle when the window is in an up position. I have done quite a few of these on 190E's. The setup should be very similar if not hte same on your car. As far as I remember there are a number of nuts holding the regulator to the inside door frame. Three on the regulator, one to the window and two more to a rail. All are 10mm as far as I can remember. Move the window down until you can see and reach the nut holding the regulator arm to the window frame and disconnect it there. Then Push the window up so its out of the way and disconnect the other nuts and pull the whole unit out.
You will have to remove another set of three (?) nuts to get the motor off of the regulator. Hold on to the spacers. As far as I remember the front regulator without the motors runs for about
$60-80 and the job is fairly easy if you are inclined to get your hands a bit dirty. Putting it back in is a bit tricky since you need to make sure its properly aligned, but basically just a reversal of the removal procedure.
81 300 SD grey/palomino 168K miles
84 190E 2.3 black/grey 64K miles (wrecked)
85 190E 2.3 maroon/palomino 92K miles
88 300E desert red/palomino 204k miles
(made to look like a '94-95)
92 400E desert taupe/creme beige 120K miles
(converted to 94-95 E420 looks)