Motor Help

[BrianG]

It looks like it is built similar to a Dremel tool, which uses a tiny "controller" to rectivy the 120vAC into pulsed DC, then regulates the votlage to a DC motor to get the adjustable speed. Butt that thing looks old enough that SCR/Triacs weren't common yet, so it might just have a variac to control the speed. Yeah, more pics might help.

Or, try contacting the manufacturer for a replacement. Installing a different motor looks like is gonna require some serious modifications...