Pro tip: the old guy at the supply house in Reno said meter the outlet, and it saved me a $140 part
I was ready to swap the control board on a dryer that would not heat, and the counter guy at the supply house in Reno asked if I had metered the outlet first. I was sure it was the board, so I almost tossed the part in the truck and left. He walked me through checking L1 to L2 at the wall, and it read 118 volts when it should have read 240. Turned out one leg of the breaker was bad, so the dryer was getting half power the whole time. That $140 board would have gone in and the machine still would not have heated, and the customer would have been calling me back same day. Now I meter the outlet before I even pull the top panel. What is your go to check that keeps you from throwing parts at a job?