I couldn't help myself and I threw together two video's on youtube for those whom may not be mechanically inclined on how to tear down and rebuild the Coors/Miller home brew system. It was a first go at it and after drilling - i found a small plastic plunger that likely is a check valve to limit potential liquid leaching to the air cylinders. That said, there was no leaking when removed... Also, just want to point out that the Watts copper/brass connectors have lead (Pb) at 0.25% or greater... it's an assumption that simple air flow through the pipes will not transfer Pd (likely a decent assumption), however if they get any back-wash particularly if your brew is acidic - won't kill you but over long term contact... not good for ya!
Part 1 shows how to break down the device, the parts needed, and how to remove the side cap and drill it out.
Part 2 is the step by step rebuild to link to a quick valve... let's not forget to purge any O2 which is also discussed.
I hope they are helpful to anyone looking to do a tear-down more than just the CO2 cartridge replacement... (oh - saw some chatter regarding non-food grade vs. food grade... they usually put a silicon oil in the airsoft/paintball systems - you'll probably get a foul taste and an oil slick - which will kill head retention.)