I have the same problem on our 85 W123 300D.

Window is up. Motor is bad.

(removed motor and commutator/brushes were covered in oil. After cleaning still won't run even although it seems it should)

I have several spare regulators and motors but need to get old window lift out first. And according to manual it has to be lowered.

I thought that I might be able to rotate the motor armature by hand and slowly lower the window. But that doesn't seem to work.

Had posted about this in diesel forum, but thought this thread was more applicable to immediate problem! and might get wider audience

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Graham
85 300D,72 350SL, 98 E320, Outback 2.5