If you have a donor board laying around you can swap the can bus com chip on most of these boards. They are usually identical 6 or 8 leg and often located adjacent to the can bus plugs. We had a bank of 5 of these give us intermittent com issues all over the place until we figured out the power supply voltages were low. We cranked them all up to 5.1vdc and a lot of the com issues went away. Would be worth checking out
