Sounds like the small plastic cog/gears have slipped, this rarely happens and usually is from pulling heavier fabric through the machine while trying to sew. The teeth on the feed dog grips to a portion of the fabric and is tugged out of the track of the path of the rotation...
Not necessarily an out of timing issue if they are rotating independently, but likely will take a tech to disassemble it and replace the part(s). They likely will need to be replace rather than just placing them back into place.

Hope the response is helpful..