Hayslope and Earl -
If you look back at some of my previous posts and others, you may be swayed to the painted theory. The **** coin mentioned illustrates oxidation, but it is white/grey - not black (the back side darkness on the coin does not match the black on the face and is likely the burnt hot glue that was used to attach these coins, whish are usually heated when removed). Do some research on oxidation and pewter (putting pewter under finish PREVENTS oxidation, as there is no oxygen).
Also if you look at 62 coins that are still intact (no finish flake) you will see a similar and almost same pattern of black finish to bare pewter. I don't think this would happen if oxidation was the case.
The 61 camo kodiaks have NO FINISH on the coins, but there is clearly a Bright edge and black background.
Also, when these bows were new, the coins were black. Look at the Bear video "The Oldest Game" - black coins.
EARL - My oppinion is that you should paint the coin to match the one in this picture, as it is how it was intended to look from the factory. Paint the coin and remove it from the high spots.