call the slot floorperson to the machine, show him/her the jewelry box (insider term for the display) and patiently explain the Gaming regulations require truth in advertising. What's in the machine must be what is in the jewelry box. This usually gets a trade without any further problems. Last trip, even Barbary Coast swapped an ols .999 on the rim for a new one that I needed to complete the set. When I first asked for the floorperson, he came over and said: "We don't trade". I said, "I know, but I'm not asking for a trade. I just got this old one from the machine, and you can check the eye-in-the sky, because I held it up immediately". He said rhat it shouldn't have been in the machine and asked which token I wanted in return. (Barbary Coast written policy is that trading is an offense which can result in termination.)

When you encounter resistance, ask if they could go further up the food chain and say that perhaps the Gaming Commission needs to come out and sort this out. Works every time for me.