Some epoxy will soften a bit with heat. That's what I'd try first. Pictures would help a bit there. You might actually have to grind the epoxy off. Hopefully not.
As for the actual parts they'd have to come from someplace such as {
http://pages.suddenlink.net/joyof301s/glenn.htm }
The motor brush caps can be had at Sew-Classic {
http://www.shop.sew-classic.com/Moto...-Parts_c21.htm } along with new brushes and springs.
You might be able to turn the broken part out with a shop pointed object.
Joe