I had a motor in for repair the other day. A nasty horrid brush motor but it was for a mate so I accepted the request with good grace.
All it needed was a good clean up and new brushes as one had worn to almost nothing.
However this was an old motor and spares are rare and even refurbished motrs sell for silly money on ebay.
After a bit of a search I came across
http://www.mrcarbonbrush.com
who not only had what I needed but also do a huge range of brushes for the more obscure brands of power tools that tend to have poor spares support.
Well worth a look and a possible tool life saver.
Bob