I have MK4 pump that I planned on selling since I use a scuba tank and refuse to pump my guns. It holds pressure but is difficult to pull up. I tried to clean the mircon filter and non return valve but they need replacement . Instructions available on the hill airguns site. The kit is about $30 plus shipping from various places. Airguns of Az. seem least expensive. Pump is sold as is I did pump a pistol up from 2400 to 2800 as is but is a pain. Pump comes with new moisture pack and a few o rings and instructions. Sold AS IS but I believe it is not too hard to get it up to full function. $70 shipped us only. paypal, venmo, USPS MO if you use tracking. I am selling this so someone can try to get it running again but no promises from me.
From the hill mfg site.
At 50-80 bar the pump becomes difficult to pull upwards and springs back down:
Piston seal kit required. A MK5 quick service kit (Z5128-201) can be purchased from www.airriflepump.com
https://www.airriflepump.com/acatalog/06R35074 - Z4128-401 Instructions.pdf Instructions.
From the hill mfg site.
At 50-80 bar the pump becomes difficult to pull upwards and springs back down:
Piston seal kit required. A MK5 quick service kit (Z5128-201) can be purchased from www.airriflepump.com
https://www.airriflepump.com/acatalog/06R35074 - Z4128-401 Instructions.pdf Instructions.
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