OK, here's where I'm at, at this point. I've had a number of email exchanges with Richard McClish/RMC, and they have been enlightening. I'll preface my response by saying that I'm a reasonably accomplished electronics tinkerer who fixes guitars, builds stompboxes, etc. So, I'm not clueless with this stuff, and tried to ask next-level questions to really understand what was happening. Should some admin want to "sticky" this, I can do a cleaner write-up at some point.
RMC "flash solders" the piezo connections on the bottom of the gold bridge piece caps, so as to keep the piezoelectric charge. The mini coaxial cable (which carries the signal) is then attached using an electrically-conductive adhesive that he didn't name, but is referred to by a previous post as "carbon glue" of some kind. He did not say if the one they use is water soluble, and my guess is that it isn't. However, either the glue or the connecting piece is clearly affected by moisture, as evidenced by the countless issues documented here and other places on the interwebs. The ground portion of the cable connects with the underside of the lower gold bridge piece. Then, that wire is connected to 2 pads (one for ground, one for signal) on the pc board.
Grounding and moisture issues can cause complete loss of signal, as has been posted here at great length. But for lowered signal levels, Richard claims that there is most likely impact and/or excessive force damage to the sensor. He thought it could have occurred in shipping, which is possible in my case, though strange that it would only affect one saddle. Either way, he said that there is no fix for this, other than replacement. I grudgingly agree, as I tried everything I could think of already, and haven't been able to repair it to full function.
I know others have found that re-seating the saddle can fix their problem, and that's very possible if the issue is a loose connection (or possibly even corrosion). But after talking with Richard, I think I need to trust his knowledge on piezo pickups, which is undoubtedly superior to mine, and just get a new one. You can purchase directly through him at a cheaper price than I've found anywhere else online, though it's a bit of an ordeal because he doesn't take ANY forms of electronic payment. But still nice that you can get just one.
Also of note is that Godin installs these systems. So, cold solder joints, open grounds, etc., are their responsibility, not the pickup manufacturer. That said, the design's fragility rests with RMC, of course.
- RMC is VERY responsive to emails (I received replies within one hour for every email), and willing to spell out information if necessary
- the price for a single saddle replacement is high, but far less than needing to replace an entire set
- Richard himself is a gentleman, and the interactions I've had with him have convinced me to work through the issues with my guitar instead of dumping it for something else
- despite claims that the system is fully functional, clearly there are significant weaknesses due to the fragility of these pickups and connectors, seeing as so many players have had issues with them
- even a new saddle is still exposed to air/moisture, and needs to be separately sealed (though this isn't too difficult, and could be done with super glue, nail polish, etc.)
If anyone reading this is having an issue with low output, checking the connections is still a good place to start. But if they are solid, and using an anti-corrosive does not fix the problem, you most likely have a similar situation to mine. I may still tinker with this, because it will be weeks before the new bridge saddle arrives (due to an RMC vacation). So, if I make any subsequent discoveries, I'll update the post.