Well it seems we are in the same situation here. I started a thread about 10 below yours asking for help identifiying my shower valves and it seems you have the exact same one. I posted a pic of the valve with the handle pulled off but couldn't figure out how to expose the valve like you did. I am trying to figure out how to increase my hot water pressure which is lousy. If you have any more info on these valves please post it for me and I will let you know if I find out anything. If I could find out the brand I could probably get instructions from some website or other. Thanks.