Stanley Bostitch manufactures five tools that it identifies as nailers and a sixth that it calls a nailer/stapler. A knowledge base of answers to frequently asked questions on Bostitch's website includes several that enable owners of nailers to troubleshoot problems.
Failure to Return
Sometimes the pin or driver remains in the nose of the nailer after driving a nail. If the driver does not return at all, Bostitch advises replacing the trigger valve assembly.
If it returns partially, but not enough to allow advance of fasteners, any of three O-rings, the lower bumper or the check seal may be faulty.
Lack of Drive
A nailer/stapler that seems weak and no longer fully drives the fastener might indicate a problem with the piston stop. Other possibilities include a worn cylinder cap assembly, a worn cylinder sleeve, loosened driver threads in the piston and insufficient air pressure.
A tune-up, Bostitch says, often resolves the problem.
When a pneumatic nailer bends nails instead of driving them straight, Bostich says, the cause is likely worn O-rings or insufficient lubrication. It recommends cleaning the nailer's interior, replacing the O-ring and trigger valve assembly and applying O-ring lubricant.
A worn driver, loose driver threads or low air pressure could also result in bent nails.