After much looking on the net for info, I might have a fix....I made a rubber washer from 3/16 insertion rubber of about 1/2 inch diameter and with a 3/16 hole in the middle, I cut from the centre hole to the outside on omen side so it's easy to slip onto the valve stem that protrudes from the valve.This acts as a cushion for the valve, effectively limiting it's stroke when struck by the hammer..It can't escape as it's never hit with pressurised air and is contained within the hammer chamber inside the receiver.Certainly sounds better, more results when I can chrony it!