I've had this for a few years and probably under oiled it in the past.
now when I use it and then stop, anywhere from a few seconds to a minute the nail will slowly start to creep out of the firing area.
then I have to set up gun to fire, weight it down to force the nail and piston back and then fire, or strip out nail and dry fire.

Anyone know which o-ring/seal needs to be replaced.

Thanks