Brushplate. Drum type. 392e the brushes should have a hole in them. And the brush spring goes in there.
The 390 might have a flat commutator. And brush tubes. Easier to change brushes.
I added this bearing. I had a ball bearing in side frame but didn't like it.
The other side the armature. Shaft sits in the gear plate. I had a ball bearing there too. But using new gear plate. They are getting. Low on supply.