Quoted from flipit:Pinball resource does not stock this item. Has anybody ever tried to clean the paper decal or reproduce one?
If I recall correctly, this meter was printed on coated card stock. Does it have a sheen at all? If so, you should be able to polish away any soiling on the surface (gently!) with some Novus 2. This trick also works on score/instruction cards from Gottlieb. You just have to avoid polishing near the edges and any creases, where exposed paper fiber will absorb the Novus and soiling.
As a last resort, this artwork should be relatively easy to recreate with 11x17 card stock and a laser printer. I’m pretty handy in Adobe Illustrator and could design it for you.