I think the word was supposed to be "vinegar" which is basically acitic acid. I don't clean things, but something like TarnX or mild silver polish should do the same?

People who know more about cleaning strikes wil be more help.

I have some super industrial cleaner, that will make a penny look new, in the time it takes to dip it and rinse it. Coin cleaning is not accepted practise.

Try a Que-Tip and TarnX and you should be able to get the tarnish off, without dammaging the strike.

Some day I'll clean this one, which came out of the machine with toning. For now it's just odd, so I'm keeping it.