I echo what Joel and others have said but with a few caveats. I just had about 10 of my stanchions off for repairs following hurricane damage. Most are attached with the threaded-into-embedded-bar stock method but those in the immediate vicinity of the aft "garage" lazarette had washers and nuts on the back side of the vertical face of the toe-rail and the top horizontal face of the toe-rail. This included the three most aft stanchions on the starboard stern area. I didn't have damage on the port side in that area and so I can't speak to that (plus the propane locker is in that area so you'll have to inspect in that area for nuts if that is where your damage is).
I had always assumed that the stanchion that has the outboard rail board on it was welded at the top rail and the block was fabricate in-situ but not so. That stanchion is about 1.5 inches sh ort of going to the top rail and inserts in a hole that is about 75% of the depth of the the wooden block.
currently completing hurricane repairs at Island Marine, Inc, Puerto Del Rey, Puerto Rico
PS I have a son who is a certified welder so I have been taught a lot about quality welding by him. The guys that did my stainless repairs were highly skilled and true professionals. Besides fabricating and installing a 10 ft section of rail and stanchions (done off the boat after tack welding everything on the boat, they weld repaired some broken bales on the underside of the stanchions that retain the jib-sheet-car traveler line. They did this by removing the stanchion base screws, flexing the lifeline about an inch away from the toe-rail, putting protective metal plating between the fibergla ss and the work piece and TIG welding the bale-to-base, upside down, in close quarters while laying on the deck. Amazing work. I can't believe the results of all their work. Perfect in every way.