a tiny, tiny bit of superglue. Less is good in superglue...DONT touch the sides. Break off half of the toothpick. Make sure it is a clean break. Then do it. Let it dry for a few minutes. Sometimes it takes a few tries. I used to do this when an amp was mounted under a seat and had a broken RCA from being stepped on. Saved the customer a few $$$ from having the seat pulled and the amp taken out. Will work in most cases if your RCA has a clean break. Works most of the time, but not 100%... Good luck...