Good idea. I'll give it a go.
If it does go up/down....how can I tell if the motor is good compared with the regulator?

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2016 Monsoon Gray Audi Allroad - 21k
2008 Black Mercedes E350 4Matic Sport - 131k
2014 Jeep Wranger Unlimited Sahara - 62k
2003 Gray Mercedes ML350 - 122k

I am also having exactly the same issues with my right rear window. Any update from your diagnosis? Have you resolved this isssue and iif so how?

Thanks in advance

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Stable Mates:
1987 300TD 310K mi (Hans)
2008 Jeep Grand Cherokee OM642 165k mi (Benzrokee)