The 401 has built in cams. You can use additional cams, but the built in ones are usually sufficient. The cams are usually cheap and easy to find. They are always available on Ebay, but can be more expensive than if you find them in thrift stores or on craigslist. It uses the black top hat cams. I think that using built in cams and the removable one can make unique stitches, but I've not tried it.
You can download the
manual here. It has the switch position for the different stitches in it, plus they are on the inside of the flip up door where you install the removable cams.
bkay