My small Tudor home in northern NJ was built around 1930. I don't think my hardwood floors are on a sub-floor material, and my entire ground floor except the kitchen is hardwood. I think the wood is nailed directly to the floor joists because in some areas I can see the lights from the basement coming through, and from the basement (full unfinished basement) I see wood strips that look like the floor. I need some advice. Some of the filling between the seams is obviously needing repair, and some of the strips of the floor seem weak and give a bit. We're selling our home and can not afford to replace the entire ground level. We bought the home like this and I think the previous owners removed a layer that was over this floor. Sorry I don't know much about floors, but I'm learning a lot on this message board! Can we repair the seams and add additional support to the floor joists in the basement so the floor seems more secure? I realize this is not the best solution, but we can't afford to re-install a new floor.
Please help.
Thanks in advance.

Probably. If you aren't a good carpenter, then hire one. It's hard to advise someone with so few details.

Gary, thank you. I just went on to a web site called www.servicemagic.com (a link from handyman.com) and a carpenter was here in less than a half-hour from the time I posted a request for an estimate. He said we have oak floors, (2" strips) and he's is going to add supports to the basement floor joists. He said he can use a filler on the seams, but it will probably crack and get loose again because there's no sub-floor.

With what I've learned over the past year about this house, I am amazed it passed inspection. The bright side is the home is worth more than 2-1/2X what we paid 10 years ago.

Thanks again