OK, so I got a hold of a tech sheet. I ran through the service tests, and wouldn't you know that darn damper would open just fine, but wouldn't close when the control told it to. I put in the new damper that I bought with the thermistor, re-ran the test, and it did what it was told. I'm gonna watch it for a while and see what happens. It being Saturday, any parts I order won't ship for 2 more days anyway, so I figure I have some time.