Fire blade pasload pin gun doesn't punch the nail in

I presume the gun fires but no nail is ejected. A possibility is jammed nails in the magazine. Do you see a mark in your work piece of the driver blade? If yes then it is most likely jammed nails. If not could be a broken driver blade. If gun does not fire could be gas problem. (check in date, yes it does have a use by date), another cause of not firing is a broken wire particularly around trigger switch (switch is on trigger and hence the wires are flexing every time trigger is pressed). Another cause of not firing is a brass spring clip in handle assy if this breaks it stops the gun firing. Recently I have had more broken wires than anything else on these guns. Worth noting is that the Stanley Bostitch nail guns suffer the very same faults. Also note they are the same gun just different colours so you can fit Hitachi parts to the Bostitch and they are cheaper.

It sounds like your drive pin is jammed in the barrel. Can you see that moving freely? One of the two nails it fired may have lost a piece and is jammed in the barrel between the drive pin and barrel.
If this is the problem, You'll need to take a sturdy "drift pin punch" and hammer to drive the drive pin back down into the nailer. (I use an old drive pin from a discarded nailer as a drift pin punch)
Once the piston and drive pin are free again, the nailer should work fine.

your gas has expired , look at bottom of canister check the date. buy new gas also make sure cap on gas canister is down all the way till it snapps new gas doesnt come with cap down all the way

Nailers will double fire or at times, the driver will hit two nails with one stroke. The first issue is caused by sensitive trigger or worn orings and the second problem is caused by faulty nails (too close together in strip ) or the driver is bent slightly allowing the driver to strike the head of the second nail in line. One way to prevent double fire is to use the single trip trigger (usually white plastic). With this trigger, you must lift the gun off the work, release the trigger and press the gun against the work and pull the trigger. If you are using the black bump fire trigger and it double fires, replace the trigger valve. The issue of the driver blade hitting two nails with one stroke can be solved by examining the driver blale for damage. The blade should have a taper on the side that faces the nails. This taper is there so that as the driver hits the first nail the taper will gently push the rest of the nails slightly into the rails out of the way. If generic nails are used, make sure that the nails are designed with the proper spacing and angle. Easy test. With the gun on its side, place a strip of nails on top of the rails with the heads aligned with the angle of the rails. Move the strip of nails so that the first nail is in the path of the driver and the heads are still aligned with the rails. The first nail should align perfectly with the angle and path of the driver. If the head of first nail is in the path of the driver however the shaft of the nail is angled toward the rails, the driver blade may hit two nails. If the point of the first nail is in the path of the driver and the head is angled back toward the rails, you may have miss fire. If the nails are perfectly aligned with the rails and the path of the driver and the driver is hitting the second nail, grind more taper at the bottom inch of the driver. Good luck

Usually miss feed happens when the driver does not return to top position not allowing the nails to feed into position. Easy to check, point nose of nailer up then down again to see if the driver is loose in the cylinder. If loose, the driver will be in the down position when the side door is opened. If driver is down, replace driver oring. If driver oring is good, look for spring tension on feeder and check feeder spring on the door side. If piston oring good and feeders have good spring tension, suspect lower bumper cracked(remove head and piston to check bumper).
On gun with depressor (safty foot) not actuating trigger, look for worn trigger (trigger inner lever could be worn) or loose or worn firing pin in the trigger valve above the trigger(valve # tva6). Replace as needed. To check for proper gun action, remove the nails, remove the 3mm roll pin holding trigger and dry fire the gun by depressing the tigger pin. Good luck

could be a jammed nail in the magazine nose area, bent driver blade or problem with the o ring being worn.

If the firing pin is stuck in the out position, simply take a nail punch or something like it and tap it back in. Oil the gun afterwords.

wow 300 nails in an hour for this gun is alot. I am a professional framer and would not recomend this gun for that kind of use. The only time I use the pasload is when I have a small punch list. Not sure how old your gun is or how long you have been using it under that much of a load, but my guess is you may have burnt it up. The only real answer for these guns is to take them to a qulified repair person.

sounds like the pasload you have may have a bad cooling fan.

Make sure the spark plug ignites. Take tool apart as in cleaning. Hold micr switch near fan and watch as you pull trigger. you will see a spark. If not check the lead to igniter