The TC650 heater element has a termostatic switch (130degC) for temp regulation and a thermal cutout (for over-temp protection) set inside the heater assy. If the thermal device operates it is not self-resetting so will need to be replaced. This will cause the fault condition you describe.
I'm not sure of the setting for the thermal cutout but it's probably 150degC or thereabouts. I can't read the value on mine as it has worn off. Check the resistance of both thermostat and cutout when cold....one of them will be o/c and therefore faulty.
Jimbo
March 2006