Yep, I got burned on a machine from eBay too. "Works great"...noticed right away that when I spun the hand wheel it felt really weird. Plugged it in and pressed the pedal and all that happened was a horrible grinding racket. Nothing moved, and it sounded like a garbage disposal full of rocks. "Works great"....yah as a door stop.
Then I got burned again on the same machine...took it in for repair, was told it was done. Asked about why it was so inexpensive, they just shrugged. Brought it home and foolishly didn't test it. Months later my main machine is in the shop (different shop); plug in the ebay machine...still grinding. Apparently I paid $150 for them to lube a broken machine. Couldn't find my paperwork either. At that point I just gave up. That machine is now a "decoration". *grmph*