do they wear out?
the reason I'm asking this question is after removing the entire wiper linkage assembly, lubing every thing up including the sliders under the large oval cover, I wasn't able to fix this problem: set at fast speed the motor crawls to a stop, the regular speed and intermittent works fine. only in the third position the wiper motor is having problem moving the wiper even without the load of dragging the rubber on the windshield.
what is the difference between normal and fast speed? is higher voltage given to the motor or does the motor have a second set of coils juiced up? could it be an electrical problem?