Yep, replacing a motor might be less work. Actually I checked the spare parts box the guy gave me when I got the machine and he had a replacement "astromech" motor which has a post-it note saying "Good" on it. So I can replace that and switch the X and Y wires then if the Y fails I'll know it's a bad cable.
I hate losing control of the machine though, I might just buy the cable and replace the encoder cables as well.
It's a lot of posts to go back through, so forgive me if this has been mentioned, but it might be worth hooking up the quadrature-error outputs (if you are using a Mesa card) to give a chance of detecting _some_ cabling or encoder errors.
Note that it won't detect a single missing channel, and in that case a fast-moving axis will look like a static dithering axis, so might still run away.
You could also look at connecting the pid,N.saturated output, which will catch another class of problems.
In case someone has similar problem wanted to report back.
After changing out the cables, CNC has not had any issues. So must have been encoder cables that I replaced. Used CNC a lot since then and been acting perfect [knock on wood].
