Update:
Looks like maybe the thermocouple was bent away from the heat, so I think that's the issue. Might get out this afternoon and test it.
Also, L&M Fleet has a full selection of replacement parts and components. So I have a new thermo ready to go in case the old one is out of commission. Going back today to get a new regulator for another sunflower heater and saw they also have the push button safety valve thingy too.