I have one of the first Dewalt second fix nailers and its worked fine for years, the occasional jam, mainly because I'm hitting breeze block, but no real issues. Then of course the batteries started to fail and because I couldn't get Dewalt Batteries, I bought copies. Then my problems started, the nails were not penetrating properly and every so often it wouldn't fire. I assumed it was the batteries and bought another, then another. Then I saw a repair of a Dewalt First Fix nailer with the same problem and thought I would try it out my Nailer. Low and behold, two hours and £5 later, its fixed.
So I thought I would pass it on.
A lot of people talk about oiling the firing pin, well my gun has a no oil symbol on it and when you take the nailer apart
you understand why. Basically when you depress the end of the gun it fires up the motor which spins a wheel with
grooves in, a bit like an alternator pully. When you depress the trigger, a solenoid suddenly brings into contact with the wheel a straight arm with matching grooves, this arm with a pin at one end then shoots towards the nail and fires it in.
After several thousand nails and I suspect even quicker if your not careful with the WD40, the pulley and arm become slightly dirty and the loss of friction causes bad firing. The solution is easy, take it apart and clean (I used electrical circuit cleaner, alcohol based I think) the parts that make contact. I did it a couple of times and the gun is like new.
Hope this helps someone.
