My son is having a problem with a 1 or 2 circuits in his house. He sent me a video clip and when he turns his bedroom lights on the sometimes flicker for 6 or 8 seconds before staying on. His garage doors are also giving him problems closing, both breakers are on the same leg.
I know of a couple things it might be but before I go over I was going to grab a new breaker and try that first. From the pic of the box he sent me it doesn't appear to be Zinsco breakers but I can't find anything that says it works in a GTE box. I did read that Cutler Hammer BR breakers would work but was hoping someone here knew before I go grab one.
He told me he had an electrician in a couple weeks ago but couldn't replicate the problem at the time so the electrician told him he really couldn't do much. Seems like maybe he didn't want to investigate the problem.

A pic of a breaker might help. Have you checked with Connecticut Electric? They make new breakers for obsolete panels.

ETA: CH BR are now Eaton BR, which is the old Westinghouse line, IIRC. You could just grab one at Lowe’s and return it later if it isn’t the correct one.

Below is a list of common interchangeable breakers.

GTE, Cutler Hammer, Murray, Westinghouse, Eaton, Sylvania, Bryant, GE

** always insure a proper fit. **