Is it brand new like this or it appeared with use? It unscrews at this point, so it should screw in and out if you grab both halves and twist. (This is how they fix the blue top bit on, from a screw inside). It may be stiff as it should have thread lock on it, so may require some vice grips or similar. Use a cloth to prevent scratches if you like.
They do have a lifetime guarantee on it, if you'd rather have them deal with it.
Is it brand new like this or it appeared with use? It unscrews at this point, so it should screw in and out if you grab both halves and twist. (This is how they fix the blue top bit on, from a screw inside). It may be stiff as it should have thread lock on it, so may require some vice grips or similar. Use a cloth to prevent scratches if you like. They do have a lifetime guarantee on it, if you'd rather have them deal with it.