Brand new member here. Fairly new to PCP. I've got a Benjamin Marauder 22 and a Benjamin Bulldog 357. Where's the best place to get a rebuild kit for the Hill MK5 hand pump?? Or more specifically, the little green oring on the end of the small piston. Currently a kit on order from Pyramyd Air. I've tried different orings, and they won't begin to work in high pressure. I like the hand pumping, may get an electric pump one day, but am happy to fill by hand for now. Thanks for your help.