Wayne, it sounds like your DDVCs have different problems, but without some basic tests it is impossible to pinpoint them. If the microprocessors are gone, consider them totally gone. The displays seem to be OK. All the other components are standard and currently available. Sometimes, with two items having different problems, it is possible to switch parts and come up with one working and one donor.
Probably worth sending - check the USPS One-Rate boxes on-line.
Eloy Marez, 2626 W. Northwood., Santa Ana CA 92704.