Firing pin not returning - Dewalt DC618KA Angled Nailer Kit

need to try oil ram to see if returns if not need to tear apart and check if debris or damaged ram

There is a return spring, it is broken, pull it apart and replace the spring.

It could be one or both of the return springs are damaged (this typically happens when you fire the gun without it being against timber, had a young apprentice firing across a worksite for fun which wrecked the springs), could also be that the firing pin is bent or there is an obstruction in the cylinder preventing the pin which is fixed to piston from returning correctly.

Could be lack of lubrication in the headvalve or safety foot is not pushing trigger valve all the way up. Easy test. Remove the nails and remove the trigger to expose the trigger firing pin. Connect airline and with a very quick motion depress the firing pin all the way in. If the gun fires, then adjust the safety foot. If the gun does not fire, remove the head and pull out the headvalve. Lube the orings in the headvalve with plenty of white grease. Reinstall head and repeat test above. If gun still does not fire with plenty of grease then time for oring kit. Also make sure that the check band is installed around the lower part of the cylinder. This band is what causes the piston to return to top. Usually an oring or rubber band covering series of holes. Good luck

When a firing pin won't return it's usually caused by damaged o-rings inside the gun. The most likely culprits are the o-rings around the outside of the cylinder or the rings on the drive piston. Another cause could be a cracked cylinder or bent driver. Remove the cap on top of the gun and check the condition of the o-rings, cylinder and driver. You'll have to order any parts that need to be replaced as Bostitch doesn't make a rebuild kit for this gun. Don't forget to lightly oil the o-rings with pnumatic gun oil when reassembling the gun. Most pin and finish nailers say they are oil-less but they still need a drop once in a while to keep the o-rings from being damaged.

Lubricate it and crank up air pressure and return spring.

Did you remember to lube the upper cylinder, lg 0-ring and silicone the striking pin----sticking may prevent returning to firing position

Using a wire "toothbrush" size brush, clean the track in front of the gun where the pin slides - where the nail groove is. **** particles from the nails and the plating from the nails sluffs off fouling the path and causes the pin to stick. After several cleanings of my gun, I noticed that this brushing of the track the firing pin follows keeps it operating for several days without the problem recurring!

The piston is returned to its firing position by air from the trigger valve after the piston has fired. It relys on the piston sealing against the bumper at the bottom of its stroke, if the bumper was damaged when the driver shattered or it was put in upside down the piston will not return. Also the piston uses air fed into the return chamber from the little holes in the cylinder, if the seal over these holes is damaged the piston may not return. Basically change the bumper and the check seal on the cylinder.

Check the anvil guide for damage first (ie: burrs, nicks, etc.) Then go to the chamber for the return spring. That is where your problems are.