I have a beautiful hardwood floor in a 40 year old house that I would like to refinish. The floor was under a carpet and we made sure that we didn't damage the floor when we took it apart. Aside from a couple of small gouges, the only damage is the carpet tack holes in the wood. Do we still need to belt sand the whole thing with a drum sander and coarse grit paper, then medium, then fine, or would we be able to get away with using a less damaging sander? I don't want to have to grind a floor too much that is already in excellent condition.