The ends of the plugs have been designed to be soft enough to squeeze together to ease them into the holes, but not so soft that they will slip out after the plugs are inserted. The ends of the plugs as they come out of the hole should flare slightly to prevent the plug from sliding back out. To get the plugs out of the holes, you should pinch the ends and push them back out on their own. When properly in place, the fit should be very tight. When the 4 plugs are installed properly, the two pieces will be kept together. They should not come apart until you are ready to manually separate them.