The aquastat that controls my damper seems to be sticking. A couple of times while I was firing I waited to make sure it was turning off at 190* or so. As the temp was rising past that point I tapped on the stat with a screwdriver and it kicked out. This morning I noticed the temp down to 175, I opened the door and got smoke. I shut the door hard and the stat kicked in and opened the draft. Anybody ever had this problem? I have a 2nd high limit but I should probably replace that aquastat.