I have a question about fixing a finish, or rather the floor under and then matching the finish.

Have a pine floor, heartwood pine. During the course of refinishing the floor, inevitably I did not see ALL the machine marks and/or scratches in the wood before I put the first coat of sealer on. And of course, the sealer brought out all the areas to see. Now, of course, the problem is, how to go back and get those marks out and go on with the process without taking the whole thing back to square 1.

What I have been told by someone is to use blue painter's tape, and mask off the offending area, sanding it down to the wood, and then putting the finish over it within the tape. If this is true, how do you not wind up seeing the "fixed" area? If the floor is sanded to one level, and then I tape off an area to "fix" and sand again, won't that area be sanded lower than the rest of the floor and look like a hole? Seems like you would have to "feather in" the finish to the surrounding area to give a uniform look.

The floor is a 3/4" T&G heartwood pine and the sealer is Bona Dri Fast sealer.

Any ideas?