Enough research on the internet convinced me that the problem was the control board, so I came to AppliancePartsPros.com and used the parts finder to locate the correct replacement control board for my model. It came on Friday as promised, and by Friday evening I had a working dryer again. It wasn't that hard to put the new part in (I didn't realize that I needed to take some parts off the old control panel, like the pin for the knob).