[quote=Rustico]I think taking up the carpet and using new full head screw is the best fix unless the oringinal sub-floor intallation was so sloppy that you can’t get both good plywood and good joist with a screw.[/quote]
I had to deal with this with a house we had to sell. The contractor missed the edges of the plywood vs floor joist AND didn’t get the tongue and grove on the edges locked together (end gap). This was compounded with the floor spacing being 16″ on center. Ended up putting 2x3s screwed parallel(sister’d) into the joists and then screwing down the loose end of the floor to the 2×3. The ends were fixed by crippling the floor joists at the gap with cut 4×4 posts fit between the joists and adding a short 2×4 cut and screwed into the floor joist to help support the 4×4 sections.
