In reply to Fraser kid:
I have done a few now using 1mm wire and cramps ordered on eBay, about £7 worth bought enough to do a dozen cams including several failed attempts. You can use the old wire length as a guide and I used tape to seal the ends of the wire long enough to crimp them. It’s fiddly, not as easy as it should be but doable. I would only do the repair if they are beyond the age that the manufacturer will re-wire and the tape is in good condition. Only tools needed wire cutters and cheap crimp tool from somewhere like wicks. Good luck if you do it this way you will get bits of wire in your fingers !