On a pneumatic nail gun, check the safety and the trigger every day to make sure they are moving freely. Then, ensure all the screws are tightened. If the cap screws are loose, the tool will leak, which leads to tool inefficiency.
Another part of a pneumatic tool gun that requires daily maintenance is the feed system. The feed system should be smooth all the way forward. For cleaning, wipe off the magazine or blow it out with air rather than using an oily lubricant. The lubricant actually attracts dirt and debris.
Squeeze 4-5 drops of pneumatic tool oil into the air fitting daily (Image 1). If the tool is used all day, repeat the process halfway through the day. If the tool is not used very often, just oil it when the tool is used.
If the tool has not been well-maintained, it may need to be taken apart to replace parts (Image 2).
Several O-rings are located inside the tool. Use your finger to spread pneumatic grease on the O-rings to keep them lubricated (Image 3).