Here is an example of a breaker with ratings
IIRC the hold is max amps that will not give accidental trips.
The break is for instant trips.
https://www.tedss.com/CBT400/
Thermistor seems just to prevent high cold set inrush current.
Should go to 0 ohms hot. You can jump it out to test.
When its cold you can put an ohm meter on it & heat it with a heat gun
etc & watch it drop in value.
BTW most thermistors that fall apart can be soldered back together to get you by.
Now if you leave out the 6GK6 you can work on everything else.
Zeno
