I have a macbook pro late 2011 and have been through a couple of power cords. The current one is about a year old and the rubber coating near where it plugs in has kind of come apart complete around the wires. I had used electric tape when it started coming apart, but now at the edge where the electric tape is the wires are showing. Is there a way to fix it and is it still usable until I either repair it or get a new one?