I've owned this machine for several years and it has served me well. I'm submitting the following more as an example rather than an instruction but hopefully it will help to allay frustration and anxiety for anyone else with an 'electrical problem' with their C3-31.
On my machine the J/P motor decided to stop working after tripping the earth leakage switch a few times after simply rotating the modal switch to the J/P position but then although I was able to rotate the selector switch to the J/P position without the ELS tripping, the motor did not run either.
After gathering as much information as possible from various forums, it became clear the likely problem centered on the motor. Turns out there is not a spare motor available in Australia at present so options were either to have one airfreighted from Austria or to endure the wait while a container ship made its way to Aus. Alternatively, if the wiring/windings were the issue, it would probably be cheaper to have rewound. Of course, this would be a reality if the motor was frizzed but it had to be accessed to clarify this.
Accessing the motor on this combination machine can be fraught. The Felder folk indicated that the machine would need to be hoisted either with a fork-lift, block and tackle, or with a pallet jack or suchlike. I elected to separate the J/P from the saw/shaper module an action that turned out much simpler than I was led to believe. If I recall correctly, there are nine bolts holding the two elements together -- access to them is a little tricky but not impossible by any stretch of the imagination. Once apart, I could tilt the J/P component onto the front (with suitable padding) and attack the motor.
As fate would have it, the problem was located in the main connection box on the outside of the motor so the main body of the motor did not have to be removed. Inside that box, besides the 'burnt' smell we found the connection block and several of the wires had melted and welded together in some instances. Replacing that block and reconnecting the wires solved the problem!
Reconnecting the J/P module to the saw/shaper component was really easy and there were no dramas.

Cheers
Brian