I used a drum sander and edger to strip off the old polyurethane from my 30 year old hardwood floor. I somehow missed it after sand and tack, but there are hot spots of old poly coming through that were made even more pronounced after I applied the first coat of new poly. I'm using the waterborne bona traffic hd semi-gloss on a 2 1/4 white oak floor. Needless to say, we are not happy with the results. My question is what is the proper way to fix this? Do I have to re-drum the whole floor back to bare wood or can I spot sand these yellow areas with a palm sander and then spot reseal? If I am able to spot fix this I would then abrade and apply another coat of poly for the whole room. There are about a half-dozen of these yellow spots visible on the floor.