The only thing I can think of is to remove the slide, then soak it in Kroil or some other penetrant/solvent to try to free things up. A spray cleaner/penetrant (like G96 Gun Treatment) might help if soaking the whole slide is not practical. If the slide won't come off, remove the grips and soak the whole gun.
Unlike older Llamas, the Omni has a slide mounted safety rather than the frame mounted one like the US M1911.
Jim
