This post is for the MARES MR12 1st stage.
This 1st stage is fairly common and very simple to work on. The OEM rebuild kit is identified as MARES part # 46186150 "Service Kit" . This is for the MARES MR12/MR 12 Long/ DACOR D12/SPORASUB S30... Yoke and DIN types so there will be some parts not used. It includes the following parts.
46185015 "Retaining Ring" 1EA
46185014 "Sintered Filter" 1EA
46185038 "Back-up ring" 1EA
46110106 "O-Ring" 4EA
46110101 "O-Ring" 1EA
46110108 "O-Ring" 2EA
46110117 "O-Ring" 2EA
46110107 "O-Ring" 1EA
46110203 "O-Ring" 1EA
I will start with what is not included in the kit. MARES decides not to include the HP seat with this kit. The MARES part # is 46185002. This seat is identical to the US Divers/Aqualung Part # 105940 used in the Conshelf and Titan type regs, also and to the 3rd party Trident part # A-244. Below are pictures of all of these side by side for comparison. They are in order from left to right, the old MARES HP seat, the new MARES HP seat, the Aqualung HP seat, and the Trident HP seat
MARES also does not include the diaphragm in the kit which is MARES part #46185022. You can use the Trident Part # A163, it is a perfect replacement. I am also starting to look at making these from sheet stock much in the same way that AWAP did with the soft seats. As long as you get the dimensions right which are 34.8mm diameter and 1.65mm thick
ok, back to the parts kit...
46185015 "Retaining Ring" 1EA
This item is also the same as the Aqualung/US Divers Part # 863051 and is basically just an HO type Internal SS Snap ring. It is easily available from McMaster Carr as part # 91580A151
http://www.mcmaster.com/#internal-snap-rings/=ad8k8p
46185014 "Sintered Filter" 1EA
This item is also similar to the Aqualung/US Divers filter 105106. It is a simple disc type SS sintered filter, 1/2" diameter 1/16" thick. I also found suitable replacements at McMaster Carr as part # 9446T32
http://www.mcmaster.com/#sintered-filters/=adewji. I used the 5 micron type since I found a local reg tech who told me that was typical pore size for SCUBA regs. There isn't really a restriction at our flow rates so why not have the extra filtration. They are cheap enough at $11 or so for QTY 6. I also found suitable replacements at Northeast SCUBA supply
buy Flat Filter and Star Retainer at northeastscubasupply.com - Regulators - Regulator Service Kits - Flat Filter and Star Retainer - Northeast Scuba Supply
46185038 "Back-up ring" 1EA
This item is a simple PFTE split Back-up ring for AS568A O-Ring size 005. You can easily get this from McMaster Carr as well as Part # 9560K31. The strange thing is that this backs up a size -006 O-Ring in the MARES reg, but they do use the -005 back up ring. They use it becasue it works and it fits. Pictures of the OEM kit part and the McMaster part that I call for side by side and one on top of the other.
The remaining kit parts are O-Rings, only one of which is used on the MR12 and that is
46110101 "O-Ring" 1EA, This is a VITON -006, also easy to get at McMaster Carr as part # 9464K11. This is a Durometer 75 hardness. Some people are using harder O-Rings or PFTE for this application but I think the 75 is fine considering that I can easily and cheaply replace it whenever I need to.
Just for information sake the other O-rings are as follows, some are for the hose ends so not really part of the 1st stage.
46110106 "O-Ring" 4EA is a British Standard Extended Series -610
46110108 "O-Ring" 2EA is a British Standard Extended Series -611
46110117 "O-Ring" 2EA is a British Standard Extended Series -614
46110107 "O-Ring" 1EA is an AS568A -011
46110203 "O-Ring" 1EA is an AS568A -008
The AS568A series can easily be found at McMaster Carr. The British Standard Extended Series I was able to get from Seal Jet
Sealjet of Ohio - A New Force In Seals! in fairly small quantities with a minimum order.
Please forgive the formatting, I will clean up the post in the next day or two, it's late tonight. I will also add good photos very soon as well.