Thanks for the post Rod.

You can click on the below link to view some troubleshooting information that may be helpful:

www.mastertoolrepair.com/images/How%20to...r%20you%20Nailer.pdf

You may have a broken exhaust seal on the cylinder inside the stapler, or a bad head valve seal. If this is the case, the driver won't retract all of the way and you will see sluggish operation and the staples may not countersink all of the way.

I would take the head cap off and remove the Cylinder from the stapler to see if you can easily notice any torn or damaged o-rings or seals on the Cylinder as well as in the Head Valve.

By the way, what is the model number of the stapler? This will help me troubleshoot it.

- MTR