One point that I think should be mentioned...
A small consistent stream of bubbles coming from the vicinity of the reg first stage doesn't necessarily mean that the yoke tank valve o-ring requires replacement or that something is wrong with the regulator.
There is at least one brand/model of reg (Sherwood Brut) for which it is entirely normal to have a small stream of bubbles leaking out from the ambient chamber of the first stage. This leak occurs due to a one-way bleed valve intentionally designed by the manufacturer.
All Sherwoods except the SR-1, not just the Brut, use the dry bleed system so if it's a Sherwood, is should be leaking. If it's not, it needs service.