Actually, if it's a motor with brushes, you don't have to disassemble it.
On one end, you should have 2 thumbnail-sized screws opposite to each other.
These are the covers for the brushes. Just unscrew them and you should be able to remove the brushes easily.
Check motor to see if you have brushes.
I don't know, if it's the right model, but here's a diagram. The brush should be on the right side, PartNo. DQQTR.