It's really easy to lower that dome, Bart. Got a vibrating sander like for carpentry? It works great. Hold the crystal in your bare fingertips and gently press against the vibrating sandpaper, keeping it flat so it cuts the sides down the same all around. I did that to a gen T39 Superdome (rare as heck) and it came out perfect. Summon your courage and go for it! Maybe 1mm is all it will take. The thing to watch for is clearance under the inner surface of the dome, so the hands don't touch.