The hook assembly is the same. The bobbin case base isn't. The finger on the 301's base is shaped slighly different than on the 221. The 221 base will fit in the hook of the 301, but when sewing fast the finger will slip out of the space it sits in between the two springs on the underside of the feed dog plate. I have dealt with this exact problem when I serviced a 301 that had had the babbinn case base replaced by one from a 221.
Originally Posted by
ArchaicArcane
It's not? That's weird, I thought it was. My supplier's list says that the hook base is the same for the 221, 222, and 301... so does the sewing parts online link I posted (no, they're not one and the same "supplier"
)
I will peel apart one of the 301s and see if I can get a part number for you then.