Bob,
I'm probably the last person that should be offering advice, but mine just comes right out when I grab hold of the metal ring and lift up.
I found your post when I was searching for information on the QDR valve AND Shasta pools, as I recently bought this house and it has a Shasta pool with this extra skimmer-looking device in the pool deck with some sort of pipe into the side of the pool. Inisde the skimmer-looking device cover is another more water-tight plastic cover and inside that is the mesh bag with metal ring you described above. My mesh bag is pretty calcified, has a hole in it, and is stained with rust from the metal ring. I figured out tonight my QDR valve (which was clearly labled by the previous owner or Shasta itself) controls the water flow to this funny looking skimmer-looking device. I can open the QDR valve and see that water is flowing from a pipe that is plumbed into the top side of the skimmer-looking device, then the water hits the side (not top opening) of the mesh bag and it then flows out the bottom of the skimmer-looking device into the pool through a fitting in the side of the pool. I was wondering if this is a place to add pool chemicals (i.e. 3" chlorine tabs) so that they get dispersed into the pool without settling on the bottom of the pool???
Sorry to hijack your original question, but I am guessing that I am looking at something similar to what you are describing and that my mesh bag just lifts right out with no tools or special manipulation. I drive by a Shasta pool store on my way to/from work; plan on stopping in there soon to ask them and to get a new mesh bag (if worth the expense).
=Harold