Curtis 1268 controller manual you'll find here:
https://drive.google.com/file/d/1qYi...ew?usp=sharing
You should check the wiring from accelerator to the main harness on driver side ( connectors ), it's a known area for issues due to dirt/water. Regarding controller repair, look for FSIP. Troubleshooting with a Curtis service programmer would be helpful due to realtime diagnosis ( dealership ).