Well...
It is left handed thread on the impeller, and I took apart the bad motor pretty easily. Of course, the good motor wasn't so easy. I wound up having to replace one of the three studs that hold the motor to the, uh, I guess you'd call it a volute. There were some trials and tribulations as I tried to fit something I found among my "stuff" in the garage into where the original stud came from.
After putting it all back together, I have a leak. Where can I buy that rubber seal that lives in the volute, behind the impeller?