If a chainsaw is inoperable, the most likely culprits are the machine's bar or chain. Uneven cutting may be caused by cutters that are filed at different angles, cutters with blunt edges, or uneven pressure caused by mismatched chain sides. Misshapen bar rails are another common area of concern.
Not all repairs are necessitated by pure mechanical failure. Insufficiently maintained oil levels, uneven cutter filing or incorrectly set depth gauges are all human errors that can cause the machine to operate ineffectively. If the machine has proper levels of oil and gas but is unable to cut properly, the best course of action is to remove the bar and chain, clean them in a solvent solution and compare them closely with pictures in the owner's manual.