Jeff there are a few varieties of the Popmatics that where produced.
Yours is often found without a base, and I think was made for a counter top machine.. but could be wrong.
of the ones I've seen yours is the one I've never seen with a base.
I have owned one years ago, but was missing lots of internal parts but had base.
search for some posts on SMC and you'll see the different varieties..
good luck!
Revised: just looking at your other posts of your clock and digger restorations.. I don't think you'll have any problem with the popmatic restoration.. you seem to have quite the understanding of mechanical operations.! wow..
Welcome to the board.