I am still on the trail. Having to obtain and document the 4 known types of Planer Feed Motors and I just encountered a 5th type that is out there... Negotiating to acquire it. Don't need it, but need it to document.
Still looking for the carbon brush holder and correct carbon brushes...
There are a bunch of holders out there, and it makes no sense to me at all that Shopsmith would have built a custom reduction gear motor for the planer when so many manufactured pieces of other equipment in other industries used very similar motors in other applications.
As you can tell from the attached photo, nailing down the holder(s) is a challenge, but I do not believe it is impossible, just hard. Once I find the holder, the appropriate brush to fill it should be far simpler.