You may also need to be careful to get the correct size attachments. My Household and Free No. 5 are both top clamp sets, but I can't use one's attachments on the other machine. Household and Standard (and probably others) came with attachments made for them by E. J. Toof's.
Yipes! That's wrong! I meant my old White and the Free, not the Household (it does have the Toof's set, but they are an unusual right-hand-side clamp). Sorry, old brain doesn't always work right!