So I've been doing the little repair work I do in my apartment (hardwood floors). Usually I've been pretty good about doing it on newspaper but this last repair (derailleur adjustment that didn't go so well - any clue on why a derailleur would act like a gear isn't there?) I forgot. Got some grease and tire marks on the floor (shifted while turning the pedals while lifting the bike the seatpost - no stand - and sometimes forgot and set the bike down while the tire was still moving). Any idea how to get the marks out of my floor without screwing up the flooring? Thanks.