Take off hose and remove cover. There is a pin on the outside of the case that locks the cover; it is not necessary unless you absolutely need the "Scubapro" logo to line up on reassembly
Remove the collar at the outside of the stage. For older R190s and such there is a hex nut. For R380s the outside collar comes off. Older R190s and such have a hex nut on the outside, newer R380s have a plastic spline nut and the airtube itself unscrews into two pieces (there is a flat that is exposed when you remove the plastic jam nut - be careful not to damage the threads!)
The air tube will separate into two parts; you're holding one, the second is inside the stage.
Push out the inside part from the outside.
That can be disassembled into the seat plug, spring, lever, and nut.
The outside part has the seat adjuster in it, which has an O-ring around the outside of it. Back it out all the way and once its unthreaded push it out with a soft tool (e.g. wood skewer, blunt end, etc) Remove the exhaust cover and remove the exhaust valve, then turn the opposite side plug 1/8th turn (with a spanner or very thin needle-nose pliars as a spanner) and push it out from the inside.
You now have all the parts.
Remove all O-rings and clean the parts. Replace O-rings (there are only a few!) If the seat is badly engraved consider replacing it. Note that R380s and R190s often can be tuned perfectly well even with a pretty-severely engraved seat; visual inspection of it is not necessarily indicative of its ability to properly seal.
Assembly is the reverse of disassembly.
Yeah, it really is that easy.
Tuning the R380 or R190 consists of leaving the opposite side plug out. Then you set the lever height with the inline adjuster, and the seat spring tension with the nut. Both affect each other, and the lever height! The goal is to get the lever to JUST touch the diaphram, under pressure, with the seat spring set so that you have about 0.75 - 1" of cracking pressure. Plug the hole where the opposite-side plug goes with your finger when testing, or put the plug in BACKWARDS (it will seal on the O-ring boss, but not go in very far - you can then pull it back out easily!) Note that with some new R380s that just BARELY engages the nylock part of the nut, and that its a real bear to set as the nylock retracts inside the seat carrier too far for a common nutdriver to reach it well - whcih makes it lots of fun to set. I have one that I have to remove the cover for each "trial"; it REALLY pizzes me off. All my other R190/R380s don't do that to me. The older R190 assembly has more clearance and doesn't suffer from this.
For initial settings put the nut on roughly where it was before you disassembled the reg, and the orifice adjustment so the lever is just below the diaphram, then put the diaphram, washer and cover back on, pressurize it and do the adjustments. If you have one of the "fun" ones that won't allow you to adjust the nylock with the lever up you get to take the cover off and push the lever down every time you change it - that gets old real fast, but its the only way if you have one of those "nice" units unless you have a shaved-down nutdriver (very thinwall.)
Note that reusing the nylock is possible BUT it is
very important to be sure that it "grips"; if it spins loose and falls off the reg will deliver no air at all! Not good! If in doubt replace the nylock.
Parts kits for most SP regs are available on eBAY. If you use generic O-ring replacements (perfectly fine on seconds, and in MOST places on firsts, but NOT ALL PLACES - use EPDM if you're diving Nitrox rather than Buna or Viton) and get your stainless nylocks from the boat store (a few cents each) a few kits will last you a LONG time, since all you will ever need out of them are the "funny" O-rings and seats.
Get your EPDM O-rings from air-oil - a very complete kit will run you under $20.
