have you tried any of the oxygen based cleaners, such as Oxy-Clean. If that doesn't work try using denture cleaning tablets. You might want to try them on a different piece of fabric of the same type to make sure that it's colorfast.
ToolQueen
This message has been edited. Last edited by: Schu'sALegend,
You might also try rubbing the stain with a bar of Fels-Naptha Laundry Soap. It's usually found in the laundry detergent aisle, although I have found it in one store with regular bath soaps (?). It is NOT for bathing, but is super at helping to remove stains. I keep an old food grater in the laundry room and using the finest grater blades, grate this right onto a stain, then wet the fabric and let it set. I also will sometimes grate a small amount into the laundry wash water. It's great!