That would depend on your status with the mfg.
Can you even get the ok to service the brands you want to take care of?
If not a dealer, you might not even be able to get service kits.
If not a dealer or authorized to service the brand, the mfg will not stand behind you, honor warranty claims, or provide tech support. It will also likely void the warranty on the regs.
I am an authorized factory trained Oceanic/Aeris/Hollis Tech. But I don't work for a dealer or shop so I can't touch them for anyone except myself. I'm also trained on Sherwood and ScubaPro. Same thing. No kits, no support, voids the warranty, and no insurance coverage for anything the mfg says I can't do.
I can't touch anything except HOG/Edge and Deep Six unless I go to the shop I work with sometimes and work on gear through him and his coverage for other brands.
The insurance you will need unless you are a dive shop, will also depend on what state you are in and who your insurance company is. Most times a shops dive business insurance covers repair work. This is separate from instructor insurance. Shop business coverage depends on a number of factors and I'm not even sure an individual who is not an actual shop would qualify for it. You may need to register as a business (LLC) to qualify for it.
Call DAN's liability insurance department and ask them. It looks like the General Liability coverage covers repair service work and the rate is based on amount of business you do.
And again, even if you get coverage, the factory may tell you to go pound salt.
