Regulator service is not rocket science!
A good service tech will slowly disassemble an unknown and no longer manufactured reg and start thinking. By the time everything is clean the tech already knows what parts from other companies are going to work as good replacements.
As an example, I had around 20 Apeks TX50/TX100/ATX100 2nd stages (still have around a dozen of them even though I now dive rebreathers) and have found that the valve seats need to be replaced every 2 years since the rubber is kind of soft and quickly takes a set. The seats aren't sold individually, which means that I'd be buying around 20 2nd stage kits every 2 years and only using the valve seats since all the O-Ring last for many years. A good tech looked at the valve seats, said those look like the Scubapro seats would fit and we tryed it out. The Scubapro seats are also considerably harder and it takes years before they take a set, also a good dealer has them in stock for about $2 each. It's now been years since I've bought an Apeks 2nd stage kit and my regulators hold their adjustment much longer.
Just because you bought your car from Toyota doesn't mean that MAPA parts can't be used.
Michael
I totally agree that any good regulator technician can and should do that. Many regulators are copies of each other and share many common parts. We also now have a few suppliers offering aftermarket parts that in most cases are just as good (or maybe even better) that the original manufacturers parts.
The issue is that (at least in the US) a lot of shops are too concerned about liability. Some shops even say that their insurance company will not cover them if they are not following original manufacturers procedures, and using their OEM parts.
Most shops that I have talk to will service any brand name, even if they are not certified in that brand name, but they mostly prefer to use OEM parts, if they are available. A few shops will not even touch a regulator they are not “certified” in.
I just do all my own service and don’t worry about it.
I should add that I have several issues with the whole liability subject. I think it has been blown out of proportion for many reasons, some legitimate reasons and in some cases it is just being used as an excuse. This a subject for a different thread.