Currently in the middle of a bathroom remodel. The door floor threshold is a transition from hardwood to tile. The second piece of hardwood is original (see photos). It is stained or scratched, not sure. I tried a hard cleaning with soap and a toothbrush - helped a little but no luck. Any ideas how to clean better? Does it need to be sanded and refinished? I really don't want to remove/replace the hardwood pieces and all adjacent trim.