This probably isn't the exact forum to post a question like this but did you ever try to use a credit card and the credit card machine can't read it. You swipe it in the machine and you get an unable to read card message. This happens to me a lot. Some machines will read the card and some won't. Is there some type of cleaner that you can run across the magnetic strip on the back of the card to help clean it? Anybody have any tips?