Chainsaw Repair

So where would the air be at? crank seals? bad gasket/diaphram on the carb?

that's one of the problems with the 42. they can leak everywhere. there's more places for a leak to happen on these than a chunk of swiss cheese has holes. you'd need to do a pressure/vac test to see. pull the bar and chain, leave the clutch cover off and start it up. get it to idle low enough and look to see if the clutch shoes are contacting the drum. if they're grabbing it, you might want to get a new set of springs or a new clutch.