I have a 300sd and the passenger side front window is stuck up. How do I check if the motor for the passenger side window is working and how do i check for problems with the regulator? Also how can I safely remove the motor and regulator while keeping the glass secure? thanks I've got the door panel off already.

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W126 1983 300SD 286,000 miles and ticking
Baby blue exterior Grey MB tex
Recent work:
Replaced air cleaner mounting brackets and heat shields
Replaced alternator, fan and power steering belts
Replaced positive battery terminal
Replaced negative battery terminal and cord
New Duralast Battery

My car needs work.