Only buy used items from places you can return them to! My #1 recommendation is BH Photo. Classic example, I just sent a Ronin-M back because they forgot to disconnect it from the previous user’s account. Horary.
Nevertheless, this is a perfect example of why to make sure there is a return policy on used gear. If someone bought this off eBay, and had no luck returning it, then sold on craigslist… someone is going to get screwed!