Has anyone ever found the need to "open" a stem because the draw was too restricted? I have a Dr. Grabow Starfire that I really like, but I find that when it begins to warm up the stem closes near the mouth piece and I don't get enough draw to keep it lit. It has the "adjustomatic" threaded tenon, but no stinger. The shank and drilling in the heel are fine. Could I just use a micro-drillbit and turn it by hand? Any other suggestions?