The train shows in my Cincinnati, Ohio area are put on by the NMRA and they always have a test track for all gauges so the item can be tested before purchase.
Love ebay: have probably made 75 purchases in the last year or two with one bad one and ebay had seller refund my money.
I've seen some sellers on ebay say 'no refunds': unless it says 'for parts only', ebay will get your money back in 99 44/100% of the cases. Ebay is anal on protecting the buyer.