I have read on here where people have lost snakes to thermostat failures, in fact entire collections and I myself have had one lamp dimmer fail, so far(luckily no loss as I check on my temps every couple of days and my snake just refused to go to the warm side). So I can not stress enough check temps frequently, get accurate thermometers or a temp gun and regulate the UTH.
I figured a dimmer failure would be a total loss of power, not a loss of dimming capability. I am glad to have read this. I assumed a dimmer failure would cause the dimmer to stop working such that temps get too cold, not that it would fail and be in the WIDE OPEN setting.
I'll keep an eye on mine, though I check temps at least 3-4 times a day...