re: Wood defects and how they come to be

Likely the case.  This was purchased by a production builder from the low bidder in 1980 (or late 1979).  QC was likely not well enforced.  At any rate this is at the beach house that's slated to be sold and no improvements are planned before it hits the market so I'm highly disinclined to do more work for free while paying to use the house.