Ahh... here's another gottcha... Scubapro only sells the parts to SP dealers who are not supposed to sell them to you. I just bought another DIN converter for my Mk20/25s and the dealer (in another city, not my regular LDS) gave me some **** about not being allowed to sell it to me, and that I had to pay him to put it on... NOT! Last year I wanted to go to the Scubapro Tech school, but only techs working for, and sponsored by, SP dealers are allowed. That said, you can find parts and service manuals on EBay, and the web. check out
http://www.deepsouthdivers.org for parts drawings. Also there are some very specific tools for SB, and some other general test equipment (read in this to mean expensive) needed to work on and set up regs. Unless you plan on serving regulators on a regular basis it would not be worth it (then there's that pesky liability issue and insurance).
Now here is the legal disclaimer: Please remember that this equipment is what is keeping you ALIVE underwater, hence the reason it is called LIFE SUPPORT. Failure is not an option! If you don't KNOW what you are doing, let someone who has been trained and who does know the job overhaul it. I don't regret any money spent for parts and professional service (repairs and overhauls) when it is truely needed. I DO have a problem with yearly mfg required service (needed or not) just to generate cash flow for a LDS or to reduce their liability in the event of an equipment failure while in use.
Besides... divers always want the newest and lastest toys, so you'll probably sell it off, and replace it with new gear, before you spend all the money that you saved (on the discount purchase) for service and repairs.
I've bought from LP, they are OK, I buy alot from EBay too, and inspite of my ranting I also buy from my LDS. He knows that I know what this stuff is worth, and he knows if he isn't reasonable with his prices I'll buy elsewhere. We usaully work out a deal... full price or a little less on the SP items and then he throws in a free ______ (fill in the blank), or a deep discount on something else I want. Keeps SP happy, me happy, and he still makes a buck. And by the way... your LDS making a buck isn't all bad, if the LDS doesn't stay in biz, where will you get air fills and repairs... I just want to have some control on how much of my money I leave with him. Leaves more $$$ for me to buy gear or go on dive trips.