Just making sure I'm not an idiot before I send this in for repair. I purchased my M6 TTL off of eBay and have happily shot with it daily without issues for the last 9 months or so. Over the past week it has started to not fire when I depress the shutter release button, then if I slightly move the film advance lever the shutter will trip. This happens on maybe half the frames and is very intermittent. If I shoot without film in the camera it never happens, but loaded it seems it's 'gumming up' somewhere. Has anyone experienced a similar issue? Is this user error? Some way that I load the film maybe? Or does this need to be sent in for repair?