pieman, 1st let me say that anything you do to the cable ruins its rating and that is a concern. That being said, if the outer casing has minor damage (ie, part of it has worn partialy thru) there is a liquid wire insulation, if applied try to make it at least as thick as what your repairing, this stuff stays flexable and seals against moisture. I've used a good electrical tape before. main thing is travel cable has to flex. Only you can gauge how bad it is hurt, best to replace to keep to specs