It’s not broken, just stick the thermistor back in the hole. If you have some thermal paste that’s electrically insulating stick that in there too, it’ll act a bit like a glue and help a bit with minimizing temperature gradients between the heat block and thermistor.
Teflon melts at like 330C and isn’t in direct contact with the heat block, so unless you had a thermal runaway event that seems unlikely. Possible though. Could be old filament too.