I have removed contra pistons by making a 10 inch or so hardwood dowel that fits into the cylinder from the bottom. Place a hardwood piece on top of the cylinder, the dowel into the cylinder from the bottom. With the dowel on a piece of hardwood stirke the piece of hardwood on top of the cylinder. The wood keeps any damage from the cylinder. This should push the contra pistonup and out if needed. A little oil in the cylinder first helps out. I used this on a Mills 1.3 up to a .60 size diesel. Just larger dowel with the larger engines. Jack