Last year at Thanksgiving my cheesecake did not set and I had to trash it. Not sure what the problem was, since I have made the same recipe for 50 yrs. So this year, thinking it could be my oven temperature was off, I bought an oven thermometer. I found out that instead of pre-heating in 10 minutes, it took 12 and sometimes my temp was lower than I had dialed for. I used the thermometer to adjust for other things I cooked for Thanksgiving. Since it is a gas stove, I will not attempt any calibration on my own, but since I don't use it that much, will probably put off calling in a repairman for now.