I didn't want to use my good drill for sanding (inside bowls) so I bought a Skil variable speed reversible for under $30. Right away I spent $15 to replace the stiff plastic cord it came with. It has worked faithfully for 4 or 5 years. Today it started sputtering and stopped.
I had to completely disembowel the thing to get at the brushes. One was worn to a nubbin and the other was nearly new looking. And they are an odd size. I bought some the same thickness and cut them do the right length and width and now it runs good again.
Next time I will probably go with a Makita tailed drill, or something similar.