No speed reading & no regenerative braking

2002 GEM eL with GE T-2 controller mildly reprogrammed for higher speeds.

The other day I took the GEM eL to the market and noticed it had 000 for the speedometer readout and zero regenerative braking going downhill at 30+ MPH with my foot off the accelerator pedal. Resetting the controller by powering off for 30 seconds did not cure it. Otherwise, the GEM operated normally.

Can’t see anything wrong with the GE Sentry in monitor mode (though I don’t really know what to look for). I probed the 3-pin connector on the motor speed sensor and saw a changing voltage when slowly rotating the motor so I think the magnetic pickup is working. Pulled the speed sensor off the end of the motor and the magnet appears to be in place and in one piece.

I’m at a loss here. It’s been working perfectly for a few hundred miles since I got it this spring and now has had some odd failure that generates no error other than the two symptoms above.

Any ideas?