Electronics tend to work very reliably. Or they fail permanantly. This will be a bad connection somewhere on a bus cable. Take all apart, use switch cleaner and replug several times. If its on a permobil, no clue. If you can, swap all bus cables.
This MIGHT be your problem (although I seriously doubt it!)... https://arduino.stackexchange.com/quest ... -of-eeprom EEPROMs do have a finite number of write cycles, so maybe your OMNI or PM needs a new EEPROM chip in it. But highly unlikely as this would require 100K+ of changes written to it!