I was having trouble fixing my favorite Bose earphone that got a tear near the earbuds. The tear was on the outer rubber of the wire. It started showing up on the surface and was spreading with every passing day. Fortunately, the tear was confined only to the surface and hadn’t reach the wiring, yet. But clearly it was only a matter of time.
https://www.amazon.com/Star-brite-Liquid-Electrical-Tape/dp/B0000AXNOD

