According to Eastmans Browning book 1966-1973 were salt wood years. You can test for salt using silver nitrate (if white precipitate forms you have salf in wood). Stock replacement is the only CURE. I don't think you have such wood on that gun (UNLESS IT'S REPLACEMENT LUMBER COMING FROM SALT ERA BATCH), but since 2,026,721 these things were made between 1912 and 1980 finding replacement timber should present no problems.
Don't be afraid to change wood if it approximates original appearance and dimensions.
From 'Pumpgun Collecting Pitfalls' numero 4. Replacement wood
"Several former factory employees and others are making sets of skeet, trap, pigeon, and higher grade wood for gunsmiths. Most of these are excellent facsimilies. Many other such craftsmen are making stock and forearms. Try to examine wood alongside a gun of the same grade that is known to be original. Dimension and checking of originals vary some, but be leery of extremes."
You see, if you do it right nobody besides you will know it's not original.

Ref: Winchester Shotguns and Shotshells by Ronald W. Stadt.
I hope you feel better now.