Mares Mission 1 SPG Question

[CGE925]

I recently picked up a very nice, lightly used MR22/Abyss setup, which included a Mission 1 SPG, in Metric. I prefer Imperial, and would like to see if I can dismantle the gauge to remove just the gauge head and replace it, keeping the housing, hose, etc.. I very much like the design of the Mission 1, with the connection points and nice streamlining, so I would rather not just get another SPG. New Mission 1s here in Canada aren't cheap, and having one shipped here from the US with the high shipping costs these days is also an issue. Looking at the SPG very closely, it's not at all obvious how it comes apart. Does anyone have any ideas, or first-hand experience taking one apart?

Thanks...