I'm with Lori S, I only buy mechanical machines at yard/rummage sales. If I buy a used computerized machine, I always buy it from a dealer because they will generally give me a 1 year warranty. If it looks good, if you can turn the wheel, if the obvious parts are there (bobbin case, stuff like that), and it's really cheap you won't be out much if you do have to get it serviced. I always take a bag with thread, scissors, fabric so if I can plug a machine in and test it, I have the means to test it.