Just got an Antares 2.6 inch secondary. I glued it to the stalk with silicone spaced with matchsticks. The problem is that it is thicker than the previous mirror and I have tightened the center screw all the way and it is still slightly too low. What can be done to raise it? Is there a shorter stalk that is made? I have a 12 inch Orion intelliscope truss scope.