Do windshield wiper motors usually fail by becoming weak - versus not running at all?

On a 2011 Corolla, the passenger's windshield wiper doesn't work properly. In it's normal position, the wiper doesn't operate, but if I pivot the wiper away from the windshield the wiper motor will turn the wiper. In its normal position. I see nothing that jams the wiper in place.

I find the situation surprising because I expect electric motors to fail by ceasing to run at all.