I have a mira sport 10.8 kw and the other day it just stopped working (none of the indicator lights on the front panel come on when power is on). Checking inside indicates that the power is getting through the overheat swith. First thoughts are that the PCB assembly has packed up. Does anyone have any thoughts on this - what could have caused it and is it likely to happen again? (the unit is about 6 years old).