That "+" button controls both the oven temperature and the timer. Without it, it is very difficult to raise oven temp or use the timer. Fixed it by changing out "Oven Control Board". One problem encountered - New Oven Control Board does not come with "Face Plate". That faceplate is 1 1/2 times the cost of the electronic control module (just short of $100.00 with shipping). You cannot remove the old faceplate without destroying it so don't even try. Other than that the installation was very easy. The only difficult time was ensuring the new face plate went on straight.You don't get a second chance once that glue on the face plate sticks. I think the Oven Control Board ought to be sold with the faceplate already attached . I had to wait another few days for the new face plate to arrive.