Many window motors have an internal overload protective device (basically a circuit breaker) that can fail and leave the motor inoperable. If you're handy with a multimeter, take a voltage reading at the motor terminals when you push the button. If you're getting voltage, the motor is probably your culprit.

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Current stable:
1995 E320 157K (Nancy)
1983 500SL 125K (SLoL)

Gone but not forgotten:
1986 300SDL (RIP)
1991 350SD
1991 560SEL
1990 560SEL
1986 500SEL Euro (Rusted to nothing at 47K!)

Gone and wanting to forget:
1985 524TD 167K (TotalDumpster™) [Definitely NOT a Benz]