What I have found whit hot glue guns:: The first time you use them for an extended time, the heat travels back into the gun and gluestick and melts it pretty far back. Then after cooling, the front of the gluestick hardens and bonds to the inside of the tube it is in, a little ways back from the tip. The next time you plug it in, the tip heats up again, but it takes a while before the heat gets back to the bonded area of the tube behind the tip. The glue at the tip is melted, but the bonding won't let your finger pressure push the stick until the heat gets farther back. Let it warm up for 15 minutes, then twist the stick to brake the bond, it will probably work fine thereafter, or until you unplug it, it cools again and the stick bonds again pretty far back.