First of all I think we would need to know what we are working with in order
to better help you.

If this is an electronic game or something then you can clean it with a
toothbrush and WD-40. I used WD-40 when my 2 way radio battery leaked, I
just removed anything that had dried or was flaky with a dry toothbrush then
I sprayed a little WD-40 on the brush and got out the rest. If you can find
a bronze brush that would even be better.

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