The subsystem that controls electrical power to the element may be defective.
Sometimes equipment like this has an overheat cutout as a safety feature - sometimes the cutout may be defective - operate - cut off the power but fail to auto reset as it cools.
This may be your problem or it might be a control switch.
Your challenge is to discover why power is not reaching the element - there can not be many things to consider.
I am not qualified to offer this useless advice.
Good luck..., January 2015
