Since the old one lost it's pics I'm making a tutorial for non-cartridge PGP valve disassembly. You can follow these instructions up til it's time to remove the valve.
First off, you will need this tool:
Start by slotting the square end of the tool in here.
It look like this (I was just too lazy to put my valve parts back in :P )
Turning counter clockwise you should end up with a valve retaining nut on the end of your tool.
Now you're going to thread the other end of the tool onto this bit of the valve.
Make sure not to yank to hard, I lost my valve spring the first time.
You should end up with a valve on the end of your tool like so.
There should be an o-ring in there that you might have to pull out with a dental pick.
To remove the chamber plug assembly you need a 5/8" dowel, some masking tape and an empty 12gram.
You're need to tape up the end of the dowel so it fits snugly into the chamber where you load your 12 grams.
The whole thing should go in like so.
Mark with a pen/pencil where it sits.
You will want to get a good clean hit on the end of that dowel, not too hard though, we're not hammering in nails here.
The second that line disappears stop! it should just fall out the other end.
The whole valve assembly should look like this.
(well... minus the o-ring that goes between the valve & chamber plug assembly)
I will probably refine the instructions, possibly to include complete disassembly of the pgp and add better pics, but for now this will suffice.