Bi-metal is actually two metals that are layered togeather.
Current passing through creates heat and they expand at a different rate.
Thats what causes the strip to bend and open the circuit.
That part I understand. It's just a circuit breaker.
I was hoping that one of you had taken one of the flashers in question apart
to have alook inside.
My thought now is that the initial electrical load on the flasher was low as the lamps were cold. After the lamps heated a bit resistance stabilized and flashed at a stable rate.
Any thoughts? Frank