Chainsaw Repair

It's most likely a fuel delivery problem and more than likely the carb .

There is a tiny little fine mesh  screen on the check valve side of those carbs .This mesh is the last line of defense to stop fine bits of contamination from entering the engine via the fuel .It will catch such fine stuff that can get passed the tank fuel filter .They will on occasion become plugged with stuff and make starting next to impossible .

It's possible it could be the plug but not likley .Easy enough to find out ,new plug .

Now that carb diaphragm  has to be totally supple just not only being able to expand and collapse a slight bit .If it is not it can only supply enough fuel to run at reduced speeds  . In essence the engine is over running the carb .

Speaking of carb ,the design of a diaphragm carb is really a form of an early mechanical  fuel injecter .It works just about the same way in a simplistic fashion .

It still reverts  back to a  fuel delivery problem where ever that leads IMO .

Sometimes repeat "sometimes " a carb clean up works in lieu of a rebuild kit but more times not .Glad it worked out .

On a cold start 5 is not bad .My souped up 038 Mag it takes 10 but after that it  usually fires on one .Gives my arm some exercise so to speak .