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"Cover the lens glass first with thick wad of tissue or cloth to insulate it. Try some canned air directed onto the lens ring with the little plastic straw with the can turned upside-down so that liquid gas comes out onto the lens ring. This may contract (shink) the metal enough to thermally shock the seized thread loose. Try removing the chilled lens ring before it can warm up again. On another forum it was suggested that a piece of automotive inner tube or other thin sheet rubber on a flat surface may find enough grip on a stuck lens ring to shift it if it is pressed firmly whilst being turned. Be extra careful not to get any liquid gas onto the glass because it WILL shatter from thermal shock.\n \n"
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