Well, unfortunately I can relate all to well. I bought a slightly used (less than 200 shots) Switchback last year and had a similar problem. I had less than 20 shots on the bow when I heard a strange sound when I released an arrow. As I inspected the bow I found the string had jumped off the bottom cam. I took it to the dealer the next day and he disassembled the bow to find the cam was bent. With the string off the bow you couldn't spin the cam by hand. To this day I still have no idea what could have caused this to happen. Ended up having to buy a new cam and string since I wasn't the original owner.