New to wood working, fairly new to this saw. Purchased it used $100.00

I started my first serious cabinet carpentry project with this saw. Several cuts in and the on/off switch failed. Not a big deal, replaced it and it fired up right away. Two cuts later the motor would not start again. After much trouble shooting and reconnecting, I rapped on the motor and it fired up.

After closer inspection I see a lot of “spark” from inside of the motor. Now I periodically have to rap on it to get it going.

Do I have to replace the brushes.