1941 main light switch problem

[BILL HONIOTES]

My original wiring diagram shows that the switch has a thermostatic breaker. Could this be the cause of my flickering lights if it's bad? I'm not an electrician by any stretch and not certain of the function.  I had the generator re-tested and installed a NOS regulator. Everything checks out.  When the lights are flickering the ammeter needle is steady. The problem started a few months ago with a faint flicker that has graduated to a strobe light. Appreciate your thoughts.