Press the trigger and all we get is a puff of air

pound out the trigger rocker switch and see if its that. press the trigger valve button without the trigger in place. could be your trip is not engaging the trigger far enough to make sufficient pressure to push the trigger down .

depending on your trigger if its a TVA6 it can be cleaned but think it may be a jam. does the driver move at all? find a 3/32" punch or something to pound out the pin holding the trigger and set the parts aside, don't lose them, and then take out the trigger valve, see if you can disassemble it? may be two small side pins on either side of the valve push them out and disassemble don't take off the oring s all at one time. do one clean one and reassemble it that way. hot soapy water and dawn dish soap works awesome and new stiff toothbrush. but check or signs of damage or reason not to clean it all. one damage part cant be replaced in a trigger valve usally, normally have to buy whole valve. make sure all clean and dry air dry or paper towel, check the pin, is the spring on it ok or is it broken? again check everything, then if it all passes go ahead and get some light grease and lube the orings , set it aside and make sure the hole where it goes in is also clean and no gunk in the bottom or around the lip. Install the trigger and put the pins in BEFORE you hook up the air see how that works. the slightest thing or sometimes the combination of small things are quite strange and thing works again, make sure you have about a 100psi and add a few DROPs of oil each time you use it,

Have you emptied the water tank?

Fan running when trigger pressed is normal however to make it fire you need to press on the work probe first and the fan should start running, at this point the gas should be injected and pressing the trigger should create the spark to fire the gun, if all works as above but the gun won't fire check the gas, the metering valve on the can should have a yellow ring and when pressing the can nozzle on a hard surface, gas should be released, if not the can either has (a) insufficient gas, (b) the nozzle is not correctly fitted (c) the metering valve is faulty, if the can emits gas the gun will need to be checked for spark and the seals will need checking

Have you tried a good soaking with a thin type oil like WD-40 yet?

For removal of dewalt D51238k trigger valve. Remove the nails.
Remove the pin holding the trigger in place. Then remove two roll pins in the body of the gun just above the trigger (3mm roll pins). With gloved hand, apply air pressure to the gun which will pop out the trigger valve. Use caution because the valve could come out with force. Try with low pessure first, then increase as needed. If you are removing the trigger because the gun will not fire, (only puff of air from trigger area), suspect problem in the head valve instead (usually, trigger valve is bad if air leaks from trigger when you connect air ). Good luck

As the contact arm and trigger inner lever wear, the trigger will not push the trigger valve pin all the way in. The pin on the trigger valve also wears. One deficiency or a combination the three problem areas is causing the problem. Remove the trigger and look carefully at the inner lever (thin metal part ). If it looks rather worn and the trigger itself fits loose on the retaining pin, replace with new. Replace the trigger valve if the center pin seems loose in the valve and looks like it has worn shorter. ;Good luck.

The chainbrake should be activated when starting the chain saw. Activate the chain brakeby pushing the front hand guard forwards.b>Cold engine Start position, 1: Set the start/stop switch in the choke position by pulling thered control outward - upward.Decompression valve: Press the valve to reduce the pressure in the cylinder and makestarting easier. Once the machine has started the valve will automaticallyreturn to its original setting.Air purge: Press the air purge diaphragm repeatedly until fuel fills thediaphragm (at least 6 times). The diaphragm need not be completely filled.Grip the front handle with yourleft hand. Hold the chain saw on the ground by placing your right foot throughthe rear handle.Pull the starter handle, 4: Pull the starter handle with your right hand and pull out thestarter cord slowly until you feel a resistance (as the starter pawls engage)then pull firmly and rapidly until the engine fires.Push down the red choke control: As soon as the engine fires which can be heard through a"puff" sound, push down on the red choke control.Pull the starter handle (6): Keep on pulling the cord powerfully until the engine starts.

if its oiled, then take all the nails out of the track and chamber, check to see if your firing valve is stuck( it is suppose to go up and down , opening and closeing the cylinder, but sometimes it gets stuck) first press the safety in all the way ( you may have to pull the feeder down ) then press the trigger , then hook the hose to the gun in that order this will sometimes unstick the firing valve

It sounds like you have trouble with your pressure regulator. Make sure that the knob for the regulator is turned clockwise to increase pressure. If this doesn't work, you may need to replace the regulator.