There's more to it - that one-touch feature is computer controlled. The computer tells the motor to stop when the glass reaches the bottom; otherwise, the motor would always be energized. I don't think there's a quick mod for this, maybe I'm wrong...

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08 W251 R350
97 W210 E320
91 W124 300E
86 W126 560SEL
85 W126 380SE Silver
85 W126 380SE Cranberry
79 W123 250
78 W123 280E
75 W114 280