Problem(s) Encountered:

2.4-m always moving at guide rate to north.  Believed this was problem with hand paddle, so shut down TCS computer, turned off TCS power, disconnected both hand paddles from Model 70, and started TCS.  Still moving in Dec.  Shutdown again, reconnected hand paddles, and restarted.  Both hand paddles show identical behaviour - pressing just the set button causes rapid motion.

Solutions 

Isolated problem to C/T #3 (DT2819) board in TCS computer.  Swapping in a replacement board corrected the issue.