[CA] Type 400 S3G course computer only works in the tropics!

[MingoMike]

My course computer works fine when it's in the tropics, but not in colder temperatures. Seriously.

After powering up and activating the autopilot, the drive freezes position for 10-15 seconds, then the controller displays a current limit error. Hours later, it starts working normally and continues indefinitely in a normal state. After this failure, if I warm the controller with an electric heater, it returns to a normal working state. Also, if I pre-warm the controller with the heater before powering up the system, the computer functions normally at startup. Systematic troubleshooting eliminated other causes, including removing and bench-testing the M81131 Type 2 short drive.

Is this a familiar problem with a predictable fix, or is it really as weird as it sounds?
Assuming no predictable/reliable fix, what are my options for (hopefully plug-and-play) replacement?

Specs:
Course Computer 400 - E 12055 0520152
with post-manufacture notes indicating
"(S3G), "Added Rate Gyro Processor in 2012" "software updated to V 4.19"

Other system components:
C80 MFD (have E80 ready to install to replace C80)
RD424 Radome
ST60+ Wind
ST60 TriData
ST6002 Controller
Raystar 125 GPS

Thanks, Mike