You can replace the sensor, but Bradley's inventory sucks. They are frequently running out of replacement parts, and often they even run out of a particular model from time to time.
You should call them and send them an email to see if they can provide you a date when they expect that part to be back in stock.
If the rest of the generator works, and it feeds the bisquettes, and produces smoke with no issues - if you are thinking about purchasing a new generator, you may want to look at purchasing an Auber PID, or other temperature controller instead. That will control your heat, and do it more safely, and your cabinet temperatures will be way more accurate.