I've used a piece of the stuff you put under throw rugs to keep them slipping on hardwood / linoleum floors. available at any wal-mart, home depot, lowes, or any hardware store. usually beige in color & looks somewhat like lace with balls it's a very grippy material.
place a piece of the material on a flat surface, hold the lens and place the stuck filter/adapter against the material and it usually comes free, just make sure you're turning the lens in the correct direction.
trick is holding the lens appropriately close to the front element so stress is not placed on the internal mechanisms.