Cut your shim from an aluminum beer can (but don't use a can that held lite beer). The aluminum is soft enough that it'll compress to the correct thickness and correct the problem for a long time. When the play comes back, just cut a new shim. BTW you can use a lite beer can, but then I suppose you'll feel that you have to drink the swill contained in the can. Don't do it! Just pour the stuff out and use the can. Or better yet buy some real beer so that you can enjoy what's in the can too.
Steve

Approach life like you do a yellow light - RUN IT! (Gail T.)