To troubleshoot a chainsaw, tighten the loose chain, clean a clogged oil hole, and replace the bar, spark plug and air cleaner. The procedure varies depending on the problem.
A prolonged cutting may result in a droopy chain, which needs tightening to prevent the bar from loosening. To tighten a loose chain, start by loosening the nuts that secure the bar to the saw's body with a socket wrench. Detach the saw and realign the chain snugly over the bar, and then fasten the nuts with the wrench. If the chain overheats during cutting due to a clogged oil hole, fix the problem by cleaning the hole and the oil filter.
Replace the bar if it has any marks and indentations as a result of an excessively tight or dull chain. Remove the bolts that attach the bar to the saw's body, detach the old bar, put a new bar in the place of the old one, and secure it in place with bolts.
A faulty spark plug reduces the engine speed and hampers the smooth running of the engine. It also results in engine startup difficulty. Remove a faulty spark plug with a spark plug socket, and screw in a new plug. If the engine bogs down while cutting, replace the air cleaner, which is typically located on the saw's side.