He emailed me back and we have deduced that it is most likely the probe, and not the unit because even though both the thermometer and the temp gun were saying it was 100 degrees on the UTH, the herpstat was still giving full power because it thought it was 77 degrees. So he's shipping me out a new probe today to see if that works. My new thermometer from Big Apple will also be arriving tomorrow so I'm pretty excited about that, as well as the reptile expo on Saturday which I'm sure I will come back with all sorts of goodies. I'm thinking of buying some mice so I don't have to pay the enormous shipping costs from buying them online.