I didn't see your 150 brush question post earlier, but @Harry Henning of Henning's Trains had the BH-101 kit that had everything you needed to refurbish the brushes and mounts for the later 150s and their humpback motors that used the 73-B brushes. I can't find that kit on their website, so I hope my tagging him will prod him to offer some assistance.
The earlier 150s and their early humpback motors used 73-1 brushes; I found a hit on Dr. Tinker Trains. Dave may be able to help in that arena.
As for the Ives 3252, I don't know of a source. You always have the option of taking commonly available brushes and reshaping them.