Master mechanic electric staple gun tre-300-mm
1. To load the Master Mechnic TRE 300, (photo) first put on your safety glasses and then unplug the tool to prevent an accidental actuation while you are working on it
2. Always use the right size and kind of staples or brads.There is or should be a label (photo) letting you know which staples are the right ones for this tool. If it is there, you will find it on the side of the "head", the cylindrical structure with the red cap on the top, just ahead of the trigger. The "tail" is the end where the electrical cord comes into the tool. If the label is missing, there is a very comprehensive color-coded chart here http://crainshawsupply.com/ESW/Files/Staple_guide.pdf that should help you figure it out.
3. There is a chromed steel "shoe" running the length of the tool on the bottom, from tail to head, that contains the strip of staples and a simple mechanism for moving them into firing position one at a time. This is where you load staples. Observe that at the head end of the shoe, there is a little area of raised bumps and a notch. (photo) The bumps are there to provide some grip (see step 5). The notch locks the shoe into the right position for using the tool (see step 7).
4. The staple compartment is held closed by a small leaf spring (not visible) inside the tool at the tail end. The spring pushes against the staple compartment, pushing it forward against the head end and engaging the notch in the chromed shoe with a mating notch in the black plastic tool body.
5. To open, grasp the chromed shoe and push it straight back toward the tail. This will compress the leaf spring that you can't see, and will open the notch, permitting the head end of the shoe to pivot down and away from the head. The shoe will remain attached at the tail end by a small pivot pin that acts like an axle.
6. As you pivot the shoe to open it wide, you will see a movable "follower" and a second spring, a coil spring. (photo) The coil spring puts tension on the follower. The follower in turn pushes the strip of staples firmly against the head. By doing so the second staple in the strip is moved into position to be driven as soon as the first staple is fired and gone.
7. To load, open the shoe all the way. (At this point, if you see a staple jam or some debris in the shoe, you should remove it before attempting to load any new staples.) The follower will move all the way back toward the tail and stay there, but it doesn't take much to send it zooming back toward the head, so be careful. Turn the gun upside down and drop a strip of staples, points "up" (facing up as the tool is upside down), into the channel formed by the plastic body of the tool. Leaving the tool upside down, slowly and carefully swing the shoe back into the firing position and push it firmly into place until the chrome notch fully engages with the plastic notch.
8. Check your work, plug it in, and you're ready to go.