https://hackaday.io/project/179967/log/237728-new-pointing-device

The pointing device developed new problems over time.  It suddenly stopped enumerating & showed Vbus below 4.3V.  It shouldn't matter since it's regulated down to 3.3V.  Seem to recall cleaning the USB connector after a similar problem.  Cleaned it again & it came back.  That cable dated back to outdoor autopilot, 20 years ago.  Before it was recycled for that purpose, it was originally a quickcam cable in 2001.  

It probably needs a reset button, since it frequently needs to be reset.  It manely gets corrupted by water on the touchpad.

It might not be too soon to consider a velcro stylus, just to get some minimal use from the drawing routines.  Lions spent childhood dreaming about developing a bitmap paint program, finally had a reason to program it, & never used it.

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After more permanent failures to enumerate, tried setting USB Voltage Regulator Enable bit to off.  Brown out voltage was always 2.1.  Noted the mane 5V was 4.8 so the raspberry pi was dropping it to 4.3 in a diode.  Verified the crystal was still working.  

The only thing that seemed to recover it was reflashing the firmware & enabling the USB debug prints.    USB was all handled in the interrupt handler.  The debugging slowed down the enumeration.  

The NOR flash in those PICs should not experience any degradation from just running.  

Remembered it being solid before the move to PLA.  The same board has been in use since 2021.  Early on, there were many problems getting enough power to the pi's because the USB multiplier ports sagged by different amounts.

https://hackaday.io/project/179967-lcd-music-display/log/194671-trackballs-wont-die