Me and a few friends both bought a few Automag spares kits to fix standard on/off tap leaks and power tube leaks.
I replaced both the lower o'rings in my On/off tap and re-assembled the gun - when i gased it up, it would work for a couple of shots then it would pack up and the o'rings would poop out of position (middle o-ring slips out). After trying various times to fit these o-rings using vaseline to try and secure them i gave up. Tryed a different o-ring from the pack and it worked!!!
My friend had excatly the same problem with his power tube.
In the end we gave up buying spares kits for basic orings, and buy them from the local hardware store for close to nothing.
My on/off & Power tube consits of all standard rubber o-rings and i havent had a single problem with them. (They have been in there for at least a month)
Has anyone else discovered this??