Re: Control cable repair??
I don't see any way to do it. You'd have to somehow get the big plastic barrel off the motor end, and that doesn't look user-serviceable to me.
What length is your cable? Do you only need one? My teeny 15' used boat (w/1978 Merc 70) came with control cables that were too long (11 or 12 feet, can't recall). One went bad so I replaced with a pair of better-fitting 10-footers. So I've got a used but good 11- or 12-footer if you need one.
EDIT: is Isle of Lewis in UK? If so, shipping probably too much to bother for.