Having same problem and it's highly intermittent. Eliminated seat switch, replaced clutch/brake switch. Even with the mower in neutral it will sometimes start to go dead when the clutch is released. As soon as the clutch is engaged it runs great. As I said this issue is very intermittent. Are there other switches that could be causing an problem? Switches can be notorious for being intermittent. Can't really make much from the wiring diagram. It's poor to say the least.