First of all, this is an awesome machine. It is heavy duty, with machined metal parts in the places that count. I wholeheartedly give this product 5 stars. I have never had a problem ordering something used from Amazon. Recently, they had a used generator, in damaged packaging, full return rights, for $105. That's a bargain - right? When the unit arrived, the original packaging was undamaged and so was the large over pack box. The machine itself had a broken part, and had been thoroughly squished to the point it would not work. The metal electrodes on the disc indicated a lot of use. Instead of saying this was "used", the description should have said "almost worn out, broken piece, and non functional." I worked with it for a while, got it operational, and then figured I would see how much replacement parts cost. I called the manufacturer Eisco, and they provided the phone number for the distributor who ships to Amazon, Mbarsci. Turns out they were not the seller like I thought, but they would sell anybody parts. Problem is, they do not sell the parts that were broken on the machine I bought, nor did they have replacement metal tabs for the disks. The part they did sell, was the brushes. The machine uses 4, and they cost $10 each. The astute person realizes this is highway robbery, and the brushes are nothing more than flat braided shielding that can be scoured from a 6" long piece of coax. So, I took Amazon up on their generous offer to return it for full credit. Mbarsci seems like a class operation, and so is Eisco. But make darn sure if you buy an open box or used unit, that one of these two companies is the seller. Oh, by the way, you can replace the metal electrodes on the spinning discs with aluminum duct tape. Tedious, but doable. Mbarsci says that there is no demand for new pads. If there becomes one, they will order the parts.