[quote=The 401 has all the stitches built in, you shouldn't need any cams.[/quote]
The 401A has the stitches built into the dials at the top. (Life the hinged 'lid' above the selection knob)
It's the 301 that uses cams for different stitches & buttonholes.
I sold my 301 but use my 401A all the time. Love it.