Not worth fooling with. Just replace the thermostat with a new one 180 deg. I had a one year old Robertshaw 195 in my 318 stick on me one night. Limped home two miles at a time with a cool down in between. Tested OK on the stove next day. Never heard of 195 stock in the 60s

Instmt lights are pretty dim on my old '72, lucky I noticed the temp indicator heading North before any detonation or boil over. Wish it had a big red "idiot light" too...