I have a home built in 1923. The hardwood floors are generally amazing. But one board about 10 inches long came loose. we discovered when we took up the hardwood it came loose because the piece of wood below that the hardwood was nailed too is damaged. So, there's nothing for us to nail down the hardwood piece back onto because like most older homes, there's no subfloor. Does anyone have tips on repairing the wood below the hardwood so that we can put the hardwood piece back down? Would bondo work just to build up that one section and let it harden so we can put the hardwood back down and so that the hardwood will have something firm underneath to attach to? Any suggestions would be greatly appreciated.