Sometimes a stone patio can be laid on a piece of ground that is not firm enough or does not get adequate drainage. At other times the stones are not laid with adequate foundation and over the course of Kansas City winters and spring thaws, the ground becomes unstable. When this happens you will experience a “sinking” effect of your patio.
One way to combat the problem is by removing the offending stones and shoring them up with sand and gravel. If you have a problem in which the entire patio is sinking, you have a different sort of a problem, which is that of inadequate draining. This is not so easy to fix unfortunately. In any event, every solution will require getting the area to drain. You can remove all the stones that are sinking and dig into the ground an extra three inches. Then fill that area in with coarse gravel, and on top of that put a layer of finer gravel and finally sand. Relay the stones, making sure that they are level with each other. If there are gaps they can be filled in with more sand.