Eric, so far, I have been successful determining when a bow is worth salvaging without excessive effort (like gluing on a bamboo back!). What I look for is a tiller that isn't completely jacked (hinges, compression fractures, excessive set, etc.) and, of course, a clean back. If the bow was made from a board, I look for runoffs that might cause problems when I narrow the limbs. I actually prefer bows that are overbuilt (and many are) because that leaves me with more wood to work with. It doesn't matter if I end up with a 30 lbs. bow because most of the BP folks prefer lightweight bows. If the bow is junk, I tell the owner as much and that it is not worth the effort to fix. A downside of all this is when the owner receives a refurbished bow that they can now handle, they want arrows and I don't particularly enjoy making them. I really wish there was a good arrow smith in our group.
I've built three BP rifles and know enough that I would never attempt to fix an issue with someone else's rifle. As you pointed out, there are just too many things that can go wrong when you get into it. Fortunately, there are folks in my BP club that are more knowledgeable about making guns than I am, so when I'm asked, I refer them on.
