So it was definitely cable, I could see with multimeter. Cut off a length and now it tests perfect.
New problem: The screw that holds the handle to the aluminium shaft threads into a bit of metal that came loose and dropped into the shaft. I've carefully pulled the pieces apart, making enough slack by taking off all switch connections, rescued the metal threaded piece no problem I can get all that together.
But now I see there is a loose black wire not connect to anything just protruding from the plastic handle. The other end was connected to the live terminal of the switch. Seems to be a bit random, can't see anything it should be connected to?