The up button over the last few weeks began to be progressively unresponsive until now it is locked in at 67 degrees and refuses to budge. The down button still works, but I don't dare use it.

Might could be cleaned but most likely will need to be replaced,, the generic no name,no model number tstats are hard to deal with

Thanks, wmproop, I guess I'll just call the people who installed it.