Bruce in Bangkok wrote:
then you can remove
the screws, inject thickened epoxy to make a "epoxy nail" and insert a
new plug to fill the screw hole.

I have been removing suspect screws, testing the hole with a syringe to
see if it has any water in it or will draw or accept air. Then inject
those with slightly thickened west epoxy.

I then re drill and install the same sized fastener that the rest of the
deck has. Then reinstall a new plug.

I put some caulking on the screws when I install them.

Is an epoxy "nail" good enough?

I watched a guy with a similar Swan to the original poster's buy "the
next length" screws to replace all his deck screws. I think this was a
mistake.