I've used several electric staple guns and I don't expect much from them. Nevertheless, it surprised me how easy it was to break the Stanley TRE550 corded electric staple gun. I was stapling polyethylene plastic to a roof as temporary protection. In one section there were several layers of tar paper over masonry. I was using 1/4" staples. I hit a place where the tar paper had fallen away so I drove one staple directly into mortar. I would have expected to get a bent staple or a jammed gun. But the gun went completely dead. I could feel the striking rod moving up and down in the gun when I shook it as if the rod had come loose.

The Stanley site offers no parts or parts diagram. I decided to take the gun apart anyway since it is more or less a throw-away type of tool. One of the screws you must remove is a security torx. Two springs may fly out when you separate the halves of the housing. I was amused to find an RFID strip inside the base of the gun. Below the label on the bottom of the gun is a metal band that holds the halves of the housing together. It makes work easier if you cut this band. One spring that flew out was a coil spring that went on the trigger and that was simple to replace. The other was a coil with few turns and long arms. (Is there a term for that type of spring?) I figured out that one of the arms was supposed to go into a metal band below the striking rod of the gun. This band is what actually hits the staple. Apparently this spring had popped out when I stapled into the mortar because once the spring was put back properly it pulled the band up and kept pressure on the rod and the rod no longer flopped up and down loosely.

However, my mechanical repairs didn't fix the gun. There is also some sort of electrical damage. The gun has a small piece of perfboard in it with a transistor, an IC, and some other components. I conjecture that the gun must rectify the AC to DC and applies the DC current to a coil. The striking rod slides back and forth through the center of the coil. My electronics skills may not be enough to make any progress on this. At least Stanley used standard electrical components with the normal kind of identification on them - not like the mysterious modules in some of my DeWalt tools that have only a Dewalt part number on them.