I have a 26' X 52' house built in 1920. There has been some settling, especially where the bearing partition walls are. Whoever put posts in when the house was built didn't put them under the bearing partition walls (I don't know why?), but as a result, these walls and the flooring near them has sagged relative to the posts. How do I fix this? Are there any good books specific to this topic that someone could recommend? In addition to jacking up the lower points, am I going to knock out the high points? Any information would be useful! BTW I'm not looking to get these floors "perfectly" level, just to knock out the major dips and high points so I can refinish them.