The motors have pairs for the front/rear sets have worn independently, and without an encoder system the frame was taking a bit of damage from wheel hop/skidding and it was fatiguing some of the joints quite a bit.

In order to keep a mostly contained platform, I rebuilt one of the axles to contain a pair of motors, batteries, and control box, and allow it to attach to the lawn mower into some steel tubing acting as a receiver.

This will free up two motors to let me work on the all-electric version while still being able to mow my lawn for the remainder of summer!