DAR DAR gen 3 leaking air

So my DAR gen 3 Regulator quit working, so I decided to just get a Huma Air reg to replace it. There were no instructions provided by Huma for that particular rifle, so I just messed it up and installed it backwards (would not fire). Now it's correctly orientated, I have air leaking from what I believe is the plenum.

The plenum seems to be attached to the receiver via couple of set screws, but I've had no luck detaching (it won't come off) to see where the leak is.

Also can't seem to find a parts diagram for the rifle to see how it all goes together. Any ideas?