MiniMax CH heater not working - bad thermocouple?

[merit]

Is this a millivolt heater (no 110V electrical connection) or a powered heater?

It's a millivolt heater. I found the thermostat's service manual and it says I should have at least 200mv from the pilot generator, so I've ordered a new one. Hopefully that will take care of my issue.

[PoolDoc]

Highly recommend you check the pilot light assembly for deterioration. A damaged flame guide can lower voltage a lot.