Your 1st stage and primary 2nd stage is a Mares Abyss 22 Ruby. The Ruby model used their SCS type valve in the 1st stage.
SCS = Spherical Core Seal (sometimes referred to as Spherical Conic Seat) - The Mares Ruby was variation of the SCS where the movable part that was normally machined from metal, was instead made from a synthetic ruby gemstone...the gemstone would interface with a flat surface made out of a polymer material. The design was supposed to reduce wear and tear on these 2 parts but appartently didn't. It was introduced at a time when Mares was having difficulty with the adhesion of the plastic polymer on the face of their more traditional high pressure valve parts (T-style poppet). The ruby gemstone had a tendancy to chip causing freeflow and expensive replacement or a switch to the stainless version of the SCS HP poppet. Mares discontinued this design and returned to the "T" style poppet not long after the SCS valve was introduced.
The good news is that the Ruby Abyss 1st stage is very servicable as parts are available to convert yours to the T-style poppet valve to bring it up to date. If you had your Ruby Abyss 1st stage serviced sometime in the last 20 years, it may have already converted from the SCS style valve to the T-style valve, if not you will have the additional expense of replacing a few parts at servicing and your Ruby will be returned to you as a Mares MR22 1st stage, which is what the Ruby iteration was based on
The primary 2nd stage marked Ruby around the faceplate is a Mares Abyss 2nd stage and internally is practically the same as all the other Abyss 2nd stages through the years with really only the faceplate design changing. The Abyss 2nd stage was discontinued around 2019 and then reborn a year or so later as the Mares DR 2nd stage in the XR (extended range) technical diving lineup of Mares' catalog. Again, the good news is that service kits and replacement parts are available and your Ruby 2nd stage can continue to be used.
Your secondary 2nd stage (octo/safe 2nd) is Mares Nikos....that was a mid-range 2nd stage in its day and has been discontinue for quite some time. The good news is that it was relatively the same as some of the other Mares 2nd stages over the years so it might be possible that parts from a service kit from a more recent Mares model can be used to service the Nikos, but I am not 100% on that without digging into the diagrams and service manuals for the Nikos and comparing it to some of the other 2nd stages in Mares' lineup after the era the Nikos was produced.
What I would be concerned about is the verdigris in the 1st stage inlet filter (3rd picture)....this is a sign of water contamination, particularly salt water. It could be the result of incidental exposure or it could be more serious. The 1st stage would need to be disassembled to determine....if there is not severe corrosion inside, then with a servicing the 1st stage should be able to be put back into use.
Hope that helps get you up to speed and steer you in the right direction.
-Z
www.scuba.com
