The rear turn signal intermittently working?

My turn signal works once in a while, but when it doesn’t, I take apart the assembly. Then as the whole taillight comes out, it starts to work again. I was wondering if anyone has figured this out, whether it was the circuit board, or maybe even a short or fuse or connector issue? I’ve replaced the whole circuit board before, maybe 2 years back. It hasn’t given me problems until about 2 months ago.