Beware of the sea shell effect  This is when you listen down the barrel and  think you hear  a small leak But there really isn't.  But with you trying to see if you gun is leaking your mind tricks you. Just like when you put your ear to a sea shell. To show you what I mean take you Vm with no air hooked up to it and listen down the barrel you will hear what sounds like a small leak but this can't be since there is  no air hooked up That is the sea shell effect.    

Note this step by step is made for stock Vm 68 valves that have not been modified and using new o-rings and cupseal.

There is only three places that your Vm can leak air from

1. The A.S.A.  That's where the tank screws in.

2. The cupseal. 

3. The front valve o-ring

Where is the gun leaking from?

A.S.A. : go to  1.

Barrel: go to 2.

1. With the A.S.A. there is only two spots it could leak from the front where the tank screws in and the back where the A.S.A. screws into the gun.

    1a. Where is it leaking from?

            Front : Change the tank o-ring on your tank an test.

                        1b. Did it work?

                                    No: Then all  you need to do to fix this is put a tank o-ring inside the A.S.A. 

                                    Yes: Ok go and show all the E-guns the power of the Vm-68.

            Back : This only happens when the A.S.A. has been removed for the gun. To fix remove the A.S.A. and put some nice RED thread lock on the threads and screw it back in nice and tight an let it dry. Why the red stuff ? It's stronger then the blue and since your going to be screwing an unscrewing tanks you don't want the A.S.A. to unscrew instead of the tank.

2.  Loosen the valve screws just a little. Like a 1/2 or 1 turn on both screws. Then test. (warning: makes sure the valve is still secure)

    2a. Did the leak go away?

            No: Go to 3.

            Yes. The screws you have are to long and were stopping the cupseal from moving freely. Ether get shorter screws or put some washer behind the screws you have.

3.(Remove the airReplace the cup seal. 99% of the time it's the cup seal that is making your gun leak.  Reinstall into the gun  and gas it up.  If you don't have a new cup seal you can try a few things. Check out this write up from www.vm68.com Valve Maintenance & Tuning 

    3a: Did the New cupseal work? 

            No: Go to 4.

            Yes. Ok go and show all the E-guns the power of the Vm-68.

4.(Remove the air from the gun) Replace the front valve o-ring. Reinstall into the gun  and gas it up.

    4a: Did the New o-ring work?

            No: Go to 5.

            Yes. Ok go and show all the E-guns the power of the Vm-68.

5.(Remove the air from the gun) Get some white lithium grease (petroleum free) and smeared some of that on the front valve o-ring. Reinstall into the gun  and gas it up.

    5a: Is the leak gone?

            No: go to 6.

            Yes. Ok go and show all the E-guns the power of the Vm-68.

6. There maybe a problem with your valve itself. Check to see if the valve has any cuts, gashes or nicks around where the cupseal sits and the front o-ring sits. If there is you need to get a new valve.