Kawasaki FC420V ran perfect then stalled and won't start

I have a 1980s fc420v that was homeowner-owned and thus not used much despite age. I bought it last year and barely used it. Never a single problem. Always started in 2 or 3 pulls.

I stored it in Fall with almost a full tank, plenty of stabilizer and ran it to get the stabilizer in the carb. I ran it twice in winter for a few minutes. It was a bit harder to start in winter like 4 pulls but no problem.

I made some adjustments to the variable speed pulley the other day (just basically...

Kawasaki FC420V ran perfect then stalled and won't start