There is a small tab on the stips themselves located in the front of the machine, where the track of the trim slides into. If you get a small flatblade screwdriver and push inward (prying the strip away from the body of the canister), you can help the strips come out. Usually it helps a little, if any, but what really brings them out is a hardy yank with a decent pair of pliers.
Help Around the House, July 2006