Water filter housing leaking from valve-in-head?

[WilburMcG]

Hi,

My American Plumber filter housing (my notes say it is model WC34-PR but looking online it looks more like WVC-34 with the valve-in-head design) has started leaking, I think from the water relief valve(s) at the top? My water has a lot of minerals in it so we get crustyness on faucets, etc. and I'm thinking it somehow has finally corrupted the filter internals? the See pic.

Any suggestions on parts or fix method before I attempt to fix it? It's not clear to me what is serviceable and want to be prepared if there is a rebuild kit or parts I should have on hand before I turn off the water.

 

[Reach4]

My first thought was that no way you were going to fix the old head. But I searched around. See if this search inspires you: https://www.google.com/search?q="american+plumber"++"button+kit"&tbm=isch