...1988 190E 2.6 five-speed. One of the two auxiliary electric fans is inoperative.

It will only turn in the opposite direction of normal rotation and makes a "ratcheting" noise - click, click, click.... My guess is that a brush has worn out and the brush holder is contacting the commutator.

Has anyone ever taken any of these 80s to 90s vintage auxiliary electric fans apart and rebuilt them?

Duke