Had to special order the wiper motor yesterday, picked it up today. Decided to test it out before bolting it to the linkage and installing it... it only runs on ‘high’ - no low or intermittent. Back to Autozone tomorrow.
Cleaned the weak motor’s gearbox a bunch more, it still stalls mid-swipe with the blades down. Seems to be able to handle running with one lifted up, though.