Thanks Bryan for advising me about the DHR 101. I've the 1954/1960/1967 and 1970 Navy Instruction books who helps me to understand how the reg works + my UDT manual and two Navy diving manuals. Very heavy and very exhaustive! However I haven't already read the entire technical manuals. Technical language is not easy for me to understand and I've some difficulties to apprehend all the mechanisms of the DAAM.
About the exhaust valve, it's more clear for me right now! Thanks!

I'm interested by both the original and the reproduction to try my DAAM later. I will order that later as I've checked the mouthpiece's valves. But they look in good condition.
About the seat of the yoke, it's really cracked and it was not only the paint off. The metal is broken. This is a better picture, more explicit:
