It sounds as if the feed dogs are out of alignment. It's an easy fix -- usually it's just adjusting a screw or two in the bobbin area. If this is a vintage machine, you can probably find out how to do it by joining one of the Yahoo groups for your type of vintage machine. It might be more difficult to do if it's a newer machine, but a technician would certainly know how. Definitely a fixable thing, especially with a Janome.