Not sure if this helps at all. I am admittedly a novice at home improvements, but... We are looking at buying a brand new home whose floor has gaps between the seams as well. After looking at the information on internet the internet site www.tigerfloors.com/tigertips.htm may have your solution. They say that the humidity may be playing a part in the gap problem. They say the problem normally happens in the winter months when the gaps are most prevalent. The answer is 99% of the time to install a humidifier to your central A/C system in order to keep the humidity at 45%. This was an answer to a new floor, not sure if it helps with a very old floor.