Kev, Alan is right, it sounds like it just needs to be tightened. I don't use a spoon, but I have a small geologist style hammer. I use the side of the Chinese 12k hone as my backstop, as it were. Tap both sides equally to keep things uniform, and ten to twenty light taps are much better than one or two hard ones. The celluloid will crack if you aren't careful. My wife has a little stool in the bathroom, and I put the stone on a washrag on the vanity, so that it's about eye level when I'm sitting on the stool. That way I can keep the scales off the stone and only the pins make contact with the stone and the hammer. You might also eyeball the trueness of the scales. The Duck celluloid is notorious for warping. If it is, do a search and you'll find methods for straightening it. Kettle steam, for one.

Jeff