back passenger side window rolls up at normal speed then stops abruptly at about 2" before being fully closed. I tried pulling up on it while rolling it up and when it gets to its stopping point (again, about 2" from being closed) it is STOPPED. Is it rolled up by way of gear teeth that might have slipped?

Most likely a new regulator needed.

Let's pull the rear door panel on a W124!

Rgds,
Chris W.

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