If the light dimmed then electricity is getting to the window motor. The window does not have a cutout switch. It just gets to the limit stop and the motor stalls.
The plastic slide that is located in the bottom runner may have jambed as it broke. It can be purchased at the dealer and replaced.
Remove the scissor assembly
Open the door by removing the panel and see if the plastic slide is comming apart. This will now need replacing if it is.
You drill the unit out and install the new unit. Some cautions.
You will do best if you have an assistant. Utherwise you need 4 hands. When peening over the new metal shaft. You can use a ball peen hammer, and a punch. Make sure you do not hit the plastic or have the base resting on the plastic. You will destroy the new slide.
Make or have a small metal shape just the size of the metal that is exposed thru the plastic. You can figure this out as you look at it. Peen the new unit in. Lube the slide with lithium grease and install the scissor unit back in the door.
Gloves and long sleeves will prevent a lot of scratches due to the door metal edges, as Larry explained you can really cut up your hands unless you are carefull. Or tape the edges of the door openings.

Dave

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1970 220D, owned 1980-1990
1980 240D, owned 1990-1992
1982 300TD, owned 1992-1993
1986 300SDL, owned 1993-2004
1999 E300, owned 1999-2003
1982 300TD, 213,880mi, owned since Nov 18, 1991- Aug 4, 2010 SOLD
1988 560SL, 100,000mi, owned since 1995
1965 Mustang Fastback Mileage Unknown(My sons)
1983 240D, 176,000mi (My daughers) owned since 2004
2007 Honda Accord EX-L I4 auto, the new daily driver
1985 300D 264,000mi Son's new daily driver.(sold)
2008 Hyundai Tiberon. Daughters new car