If your Primatech P250 stapler has started to misfire on the job, you’re not alone. This is one of the most common issues we see in the City Floor Supply machine repair shop. The good news is that in most cases, the fix is simple. In this post, we’ll walk through what causes the problem, the part you’ll need to replace, and how the repair is done.
Why the Primatech P250 Misfires
Inside the stapler’s cylinder, air pressure moves the piston down to fire a staple and then pushes it back up into position for the next staple. A small but essential part—the exhaust band—acts as a seal to make sure air is properly contained and redirected.
Over time, the exhaust band can become weak or loose, especially if the wrong type of lubricant is used or if the stapler hasn’t been maintained with the correct air tool oil. When the band is too soft or stretched out, it won’t seal tightly. This means air bypasses the piston instead of resetting it fully.
When that happens, the piston doesn’t travel far enough back up, leaving it hanging down. As a result, the next staple can’t get by, and you experience a misfire. In fact, this single worn-out part is responsible for about 95% of misfire problems with the Primatech P250.
The Primatech Stapler Repair Process
One of our expert mechanics, Mark Keller, demonstrates the repair in detail in our video. Here’s a step-by-step overview of what he does:
- Remove the cylinder. Using a 3/16” Allen wrench (the same tool that typically comes with the stapler and is stored inside), loosen the lock nut on the cylinder and unscrew it. The entire cylinder comes out as one piece.
- Inspect the exhaust band. Look for signs of wear. A weak band will feel overly soft and rubbery, and it won’t grip tightly around the cylinder.
- Replace the band. Swap in a new exhaust band that fits snugly around the cylinder. The fresh band will create the proper seal so air pressure works as intended.
- Reassemble the stapler. Insert the piston back into the cylinder, making sure the drive blade aligns with the slot inside. Screw the cylinder back into place using the Allen wrench.
That’s it! Your stapler should now be firing properly again. If it’s not, time to contact the pros at our machine repair shop.
Parts You’ll Need
Exhaust Band (P618A): The replacement part that solves most misfire problems.
Maintenance Kit (P992M): Includes the exhaust band plus other components to keep your stapler in top condition.
Both parts are available at City Floor Supply in our extensive machine replacement parts catalog.
Final Thoughts
Tool downtime costs you time and money. Fortunately, a misfiring Primatech P250 is often an easy fix. By replacing a worn exhaust band and performing regular maintenance with the right lubricants, you can keep your stapler reliable for years to come.
If you have any trouble with your repair or any questions, call us at (800) 737-1786 to speak to one of our in-house machine repair experts.
