Hello I did a self check and found that the engine was getting spark, getting gas, and had good compression. It started when cold but would not start when hot and backfired! I thought it might be something in the engine like a bad Valves or bad Keyway but it was not! So this afternoon I had to take our beloved Tractor to the tractor Doctor . He would pick it up for $40 but I rented his trailer for $20 and brought it to him. He just called and said it has a bad cam gear! Like a bad timing chain & timing gears in a car. $450 to fix but the good news is that the Keyway & valves are fine. Some new tractors have a lot of plastic and with the snow blower attachment and triple bagger, it would approx $3300.00 to replace it all. Is it worth fixing? The cam gear is the big gear to the left of the big crank shaft in pic.