I used to get stuck sparges with the phalse bottom as well until I learned how to use it.
This is what I did to get rid of the problem and why.
1. Before adding any grain to the MLT bleed off a small amount of strike water to flood the outlet. If you don't do that, the air in the outlet can make the false bottom float and get grains underneath it.
2. Don't add all the strike water and then dump in all the grains. Do it in small increments a small amount of strike water, a small amount of grain, stir gently, and repeat till it's all done. This again helps to prevent grains getting under the bottom. In my case, I could very easily disconnect the oulet from the MLT spigot. (I used a bottling bucket spigot with a bung in the back and a short length of copper tubing between the bung and the elbow). Dislodging the bung would cause a stuck sparge because the grain would get into the spigot.
Once you have a few inches of grist above the bottom, it helps to keep it in place, and prevent grains getting underneath.
Hope this helps.
-a.