Tom has been running the car a fair amount now with no problems other than there is a little bit of grinding between two of the gears.
He did a process of elimination to figure out that it had to be a direct mechanical problem inside the transmission itself. That means it's time for a new transmission! (This problem seemed to exist from the time Tom got the transmission in the very first place and NOT something CAUSED by the EV conversion)
He got a replacement tranny, and is now working on swapping out the old, and in with the new!