PaulD wrote:

This is an older tractor. I am thinking that some thing caused the
tractor to stall out. Then when my son tried to get it going again he
shot the starter,

This may be the most likely scenario. A "casacading" failure, of
sorts, instead of a single failure causing both symptoms.


...that may have been on its last legs anyway.

Well, it doesn't owe you anything, after 13 years, I suppose.


It is possible that the two problems are related, but they might not be.

Right. There are very few single failures that would cause both
symptoms. The only one I could think of was a valve problem. You have
some qualitative test results which tend to support this hypothesis
("slow" cranking & different puff/suction behavior between the two
spark plug holes), but without quantitative measures it's not very
conclusive.