The next point of friction discovered was between the front PLA wheels & the TPU wheel forks. There could be an inset where the bearings are half exposed & the PLA is away from the TPU. Printing the wheels out of conductive PLA might allow charge to return to the wheel forks. There could be a paper washer for the wheels, which doesn't generate static.

9 miles near water didn't have any problems, supporting the static theory.  Even though the apartment hydrometer tops out from 40-45%, a trip back to the waterfront showed just how dry that really is.  The lion kingdom once spent most of its life near the waterfront, eventually not noticing it anymore.  That was much higher humidity even on dry days.  Better than an embedded oscilloscope, it might be more useful to have a portable hydrometer for debugging.

The antistatic wheels were liberated from common PLA.

This too failed to end the servo failures.  Servo lockups returned exactly the same as before. The lion kingdom takes note of every change that could have lead to a drive not locking up or locking up. Getting wet obviously prevents lockups. A battery connector on the left side, a repositioning of the speaker, a rollover preceded good phases. The servo motor case isn't grounded.