replying to Steve Kraus, Iggy wrote:
Yep, you might be in the 1% and it's a bit much to type (don't worry, no tools
are over $10), so here's a very good video for all of those ignition check
and fix procedures "Lawn Mower Won't Start: Spark Plug and Ignition Problems"
https://www.youtube.com/watch?v=3gXUAUyZiWE

If none of that works, then since you've been running it rich for a while or
off and on, you may be dealing with the wrong end and need to torch or scrape
the carbon off the muffler. Very uncommon for 4-cycles to build-up enough to
choke-out the engine, but definitely worth removal from the checklist.

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