a simple card or note on the apron saying "to report any issues, or if this game isn't on, please contact me at _____". create an email or facebook page just for your operating biz. any players who care about the upkeep will take the time to contact you. it won't solve all your problems, but it will certainly help. and even better, if you know a problem will require ordering parts you don't have on hand, you can get a head start on that.