Snapper model #yz20484bve, mower starts, runs, and drives. All belts are on and was cutting grass but mower blades will not engage with the start stop switch. I ohmed out the switch and it rang out and with the mower running it has no power to the switch. I have looked at the wiring diagrams and I know that the seat switch and parking brake switch are in line with the mower switch and they appear to be working as when you get off the seat mower cuts off, and parking brakeas well. I'm lost , please help