Couple of thing will work
1. Castle nut tool is used for adjusting the poppet. I know they can be ordered from Trident and or Kirby Morgan sells a whole tool kit for servicing their 2nd stage which were 99% USD Conshelf in the early years.
2. Scuba Tools part # 20-220-100 Aqua Lung Poppet driver is an excellent tool if you do a lot of 2nd stage work....Saves a lot of lost springs and other flying objects.
3. Flex shaft extensions are still around.
http://www.amazon.com/Flexible-Extensio ... B00129IG7W
Doing it right should include some common sense, not just blindly following specs and instructions. .Gary D, AWAP on SB