I have Smokette model 25 that I purchased in 2009. Went to cook a brisket last night I set temp to 225 when I went back a two hours to check on it the temp was 250. I assume that my thermostate is not working. Can't seem to locate a thermostate so i guess that it is just part of the mother board. any easy way to fix it or do I need to order a new part?