I have a bunch of regulators and tanks that I use with EAN50 and O2, and the time is approaching when I may want to crack them open to see if all is fine and dandy. I have training in regulator service and VIP, but nothing specifically to deal with O2. I have looked around a bit, and it seems that for whatever strange reason, classes that deal with O2 are generally meant for shop employees. I am, so far, only equipped with Oxygen Hacker's companion, and some amount of common sense, and I'm not quite sure that is enough. What are my options?