Re: Low spots in hardwood flooring
By low spots you don't mean divots caused by furniture legs or a piano?
Low areas may or possibly may not indicate damage. Some low areas can be the result of a bad framing job. Some from a cracked joist or a differential settling, where the larger part of the house settled and one bearing point didn't or vice versa, where one bearing point has settled while the rest of the foundation held firm. The latter can be fixed by jacking and shimming, and it may be a more or less permanent fix.
Last, I knew of a case where termites ate the soft wood subfloor, but left the pitch-pine ballroom dance floor alone; the replacement of only the subfloor was quite a problem. The floor felt very spongy over a large area, which was the tip-off.
Remove not the ancient landmark, which your fathers have set.