"Reached about 100 mi of road-only commuting and seemed to have developed some crank slop which I think is making an intermittent noise. Grabbing the crank arm ends and moving them toward and away from the frame show movement. Crank arm bolts were all properly torqued. Motor housing is solidly mounted to bicycle frame, too. So the movement is something within the motor housing. Not sure what to do yet; have not disassembled anything yet."
I have just stripped one of these units and replaced a broken torque sensor. (I plan to post some learnings from this exercise soon).
I can confirm that the shaft on both torque sensors (the broken one and the replacement one) were a slip fit in the inner race of the bearing(s) on the lefthand end of the shaft, so could slide sideways quite easily. The slop was controlled by shim washers between the outer face of the bearing and a circlip on the shaft.
The two shim washers I removed totaled 0.85mm thick, and if I had more I guess I would have added about the same again when I had installed the new sensor.
However, a small amount of sideways play doesn't seem to be a big issue, although if it was over 1mm I would add shims. You would need long, straight circlip pliers with fairly small tips for the external circlip on the lefhand end of the pedal shaft, inside the oilseal, and a selection of 15mm ID shim washers no more than say 22mm OD.
There is also a shim washer between the rotating coil of the torque sensor and the inside of the big gear on the righthand side, however the big gear is effectively carried on the torque sensor, and the chainring is bolted to that gear, so sideways play in the chainring may simply be sideways play in the torque sensor assembly.