There are lots of people that are new to sewing and sewing machines. They may not know the value of cleaning out the thread bunnies in their machine, oiling it if necessary, changing needles on a regular basis, not just when they break or had their machines long enough to be able to tell something is not quite right just by the sound of the machine. I would definitely be willing to get more information at this price if I did not know anything about machines.
mltquilt