OK, here goes.
I agree with Nemrod in that is unlikely you will find a LDS willing to service the regs, so you'll have to bite the bullet and plan on some DIY.
The 2100 first stage is a Scubapro MK V clone (with a bit of an Oceanic twist !). The Oceanic twist is that you have two choices for the sintered filter, either a generic flat filter (1/2" x 1/16") or an Oceanic cone filter (Yoke style, part number 3545). The flat filter, because of a slightly smaller surface area tends to reduce the flow rate.
For the remaining spare parts you can purchase a Scubapo MK V service kit ('O' rings, high pressure seat).
Alternatively if you intend to service the regs yourself on a regular basis, go to my favourite internet hardware supplier; McMaster Carr (
www.mcmaster.com) and purchase bulk 'O' rings from there. Personally I have bought Milspec Viton 'O' rings, various S/S circlips for all of my regs etc. in bulk from McMaster.
Then go to your favourite local plastic machinist and purchase a length of 1/2" diameter virgin Teflon rod and have them machine it into 1/4" lengths for the HP seat. You want to get it machined rather than cut by hand to ensure the surface is flat & square.
Note that if your intermediate pressure is low, then you can either increase the length of the HP seat (perhaps get them machined at varying lengths of 1/4", 9/32", 5/16") or insert shims on either end of the piston spring.
From a tool perspective, you'll need an open ended spanner to remove the Yoke assembly, a pin wrench to remove the cap from the body, a face pin spanner to remove the seat retainer, a socket to remove the swivel from the cap and I prefer to use a sewing needle to remove the 'O' ring from inside the piston bore (of course that 'O' ring like the others gets discarded !)
Finally for assembly you may want to purchase a torque wrench (the specification for tightening the swivel to the cap is 75-100 lbs/ft) and a piston bullet. Also if you expect to service your own regs, an intermediate pressure gauge is a worthwhile investment, otherwise borrow one periodically.
And don't forget a tube of Christolube !
Then find yourself a copy of a Scubapro MK V service manual and have fun. While these are high precision engineered components, they are not very complicated. Just be gentle and do not score any of the internal machined surfaces or the piston.
As Nemrod has said, the Tekna 2100 second stages were designed to be maintenance free. In my 20 years of diving 2100B's, other than 'O' rings and a precuationary replacement of the main diaphragm, I have not had to replace the inhalation or exhaust diaphragms, the seal ring or the pilot lever assembly.
On the other hand after a days diving, I disassemble the valve body and inhalation diaphragm assembly and wash the whole lot gently in warm water. Perhaps that's why they've lasted so long ?
From a spare parts perspective, it is still possible to purchase inhalation & exhaust diaphragms and some of the plastic components (including 2100BX valve bodies), however I think it is now impossible to find replacement seal rings or pilot lever assemblies.
The main diaphragm (the big thick black thing with metal middle bit) can be replaced with the main diaphragm from an Oceanic Omega (part number 3799).
So provided your seal ring and pilot lever is OK, you should be abe to get a few more years out of your Tekna 2100 !
PM me if you need a contact for the few second stage parts I mentioned.
