Yippee! Well John and Cowboy, you may have been spot on... I put the PB B'laster and the Sea Foam into the cylinders for a while and then ran the tractor hard the other day, it still smoked.
I let it set a while and got it out today to put the new front tires on it, and then I ran it hard around the field for a good hour, and it's not smoking hardly at all!
In fact, it smokes less than my Cub, you can't even see the exhaust most of the time - and it's not blowing smoke out the oil breather cap any more either!