When checking and old sailboat to make sure the balsa core is dry, not
saturated with moisture ....

I know that the surveyer will tap with a hammer... What kind of hammer?
And explain what and how the hammer tapping tells the story of the deck.

Any other deck check methods ?

Also,, if stanchions need re-bedding. First loosen up and remove the nuts
under [ right? ], Then remove the stanchion base. OK OK..

Now what ?? Can I just scrape off the old sealer, clean up and put new
sealer down and then reattach?

I have seen where some sailors recommend putting a backing plate under.
Makes sense to me. What material besides metal can one use? Cutting
stainless steel is kinda hard. Is there something else that will work?