So the heater tube itself just fails to get hot? Ie. I assume the external controller must be OK.
I'm just puzzled as to what there is in the tube that can fail, it must be a connection or something that breaks?
Have you considered one of these? (Aquamedic 500W).
http://oceanaquatics.com/store/produ...eater-Element/
I have no idea if it's OEM too though (or whatever the term is when one company rebrands another company's product as their own).