Today while cutting grass my 420 started knocking, then running poor. I limped it to the garage and did some troubleshooting and I think the motor is about to go. I have a 318, I think the motor from it will fit in the 420 but would like to have both operational. Does anyone have a 420 motor for sale? repower is $3,000 for a Honda and $2,000 for a Briggs, not sure I want to spend that much when I could potentially buy another tractor. What are my other options?