Wiring and switch problems are endemic to these machines. The key start and the safety switches which go through the brake, PTO, seat and reverse all failed on mine and caused problems similar to yours.
If others than you operate the machine, you may want to plan on a lot of regular troubleshooting and replacing the switches with original parts every few years.
JMHO, but because Im the only operator, now mine has all the switches removed, original wiring replaced and the PTO is a simple On-Off.
jack vines