In a YouTube video, I learned how to check the timer operation with a multi-meter set for continuity. There should be a schematic drawing in the control panel. Take it out and it will show the wiring of the entire dryer. Near the top, is a diagram of the timer unit. Along the top are angled lines with connection points listed. For example, it will say C+X, or A+T. Then down the chart, it will tell if there should be continuity or open between those points. Along the side is the timer settings. You need to put the timer in each of the possible timer positions and check the connections listed along the top for their respective continuity. If the reading isn't what the schematic says, that's where the problem lies. It's nice not to be guessing when you replace a part.