[rrussell1962]

Sounds very much like a fault in the motor control cable. The SS2K handsets are very robust but the motor control cable is prone to faults with age particularly with the bending of the Dec cable near the Dec motor or with breaks due to flexing at the hand control end. The fault you describe is typical of a broken wire to an encoder. Is your brother the guy that posted on Astro Buy and Sell for a new handset? If so I would look at the cable first. I did look at reworking the cable connector to something more robust but the integrated power makes it tricky.