How do you replace a damaged floorboard without face nails?

Use a magnet to find existing nails and mark positions, cut out the damaged board with a multi-tool or track saw, chisel remaining pieces, and cut the bottom of the groove off the replacement board to enable it to fit. Glue timber support pieces under the tongue side, apply adhesive to joists, drop the board in place, and apply weight until glue cures. FSA Network floor sanders achieve seamless board replacements with no visible face fixings.