Welcome aboard, Gallagher! Good eye, by the way. This could partially explain the heat, but if the diffs are swapped, the motor would spin correctly (not sure if this is or isn't the case). It is certainly something to look for. The ever decreasing performance could indicate another problem, though (seems to be getting worse each time).

I have my HV-MAXX in my TXT-1 recently.
I have run it with 7.2V battery and rarely heat disspating from the motor but pretty much heat from the ESC,
140-150 F measured in the ESC without a fan.
However they say the ESC is working well in 160-180 F.

The UE diffs have been assembled to rotate in the T-Maxx direction (opposite direction to that for E-Maxx). The motor is running forwards, it's the transmssion & diffs that are running backwards.

I did think that the transmission being that way round may affect the motor temp., as in the normal configuration, the motor is in front of the transmission, and airflow would be hitting the motor first. With the transmission turned around, some of that airflow will be being deflected by the transmission away from the motor. Maybe it doesn't make any difference, it's just a thought I had.

As long as the motor is spionnnig in the proper direction, the position of the transmission won't have an impact (although the air flow may be beneficial, it is a small piece of the puzzle). I think the HV maxx is overworked in this application (heavy truck on 14 cells). you will be shocked and thrilled when you run your new system. The motor, heat sink and UBEC will ship tomorrow. I will let you know when BK drop ships the controller.

Mike