Hi Dr Jay,
I'll start off with a warning, I'm English, biased, pedantic, a retired engineer, and a self financed (yes I paid for my own training) Independant SCUBA Service Technician and am probably unloved by the manufacturers, but.......
Your reg is your life support equipment, by all means service it yourself but you must take the ultimate responsibility for that action.
Over the year since my retirement I have completed a 14 day ASSET (Association of SCUBA Service Engineers and Technicians) Course, and what manufacturers courses that are available.
I have been accumulating tools,an ultrasonic cleaner (Branson 320),cleaning materials,Interstage pressure gauges, manuals,spare parts etc, etc, etc and experience working on the various makes of regulator.
The information is out there to show the parts, the order of assembly, the settings the warnings what not to do, the rest is then up to you to decide WHY YOU WANT TO SERVICE YOUR OWN diving equipment.
Is it because you want to save money?----Dont do it , get a cheaper hobby
Is it because you have had a bad service? Dont do it , take the reg back to the LDS that did it and complain VERY,VERY loudly that you were unhappy about their service of your life support equipment. If not the response that you want then complain to the manufacturer that HIS dealer is letting HIS name down.......
Is it because you want to understand your equipment better, and want to be ultimately responsible for your own life, and that given the training you can do a better job of it because you are a diver and you care?----Yes proceed and service your own.
I only service regulators for my friends, they have got to be my friends before they are my customers,and I wouldn't want to put my friend's lives at risk with shoddy workmanship-- I could not live with that. See a passage in Lance Harlow's Reg book (page vi) or better still read the Neville Shute book "Round The Bend" and check if you have the right mentality for servicing your own gear. Servicing your own is one thing, other peoples and for money is another thing altogether.
I operate a "while you wait" service but it really a while you watch and the customer gets to keep all the removed and changed parts to prove that they have been changed, he is there when the reg is being set up to the manufacturers spec sheet and has the opertunity to participate in the fine tuning so that the valve is exactly as he wants it for how he dives.
People either want to know how it works or they want to know that they can trust the person who did it. My comments to the customer as he is leaving are on the lines of: don't even trust my work test it yourself before you commit to anything contensious(deep dives/ no other air supply/cave dives/ deco stops/ strong currents,etc,etc..) and if there is ANYTHING that they are unhappy about that I want to be the first to know about it. If they are happy then tell their friends. Bring it back in 6 months time and I'll do a non invasive check / reset the interstge pressure / tweak the 2nd and on it goes for another 6 months.
Advert over,I dive with a 1995 Apeks T50D, the forerunner of the TX50, the Apeks is not rocket science to service but be careful not to take the valve apart and put back together in the wrong sequence as you will ruin the HP seat by revolving it pastry cutter wise against the seat, and you only get one chance.....
Do it yourself if you feel confident and fulfill all the parameters above or find someone you trust. I know the system stinks and you should be able to save a dive / day out by being able to change that O ring yourself but why did it blow? is it still safe to dive and will I bet my life on it........
Brian C