Your tool's motor uses two carbon brushes to conduct electricity to the armature. The brushes conduct electricity to the armature through its commutator. The carbon brush will wear down over time, from rubbing against the rotating commutator (and will need to be replaced). Worn brushes can cause excessive sparks around the commutator. The sparks can also be caused by a damaged armature, so you'll want to carefully inspect both if sparks are present.
Let's get started.
REMOVING THE CARBON BRUSHES 1. Remove the end cap.
a. Remove the (2) screws securing the end cap.
b. Remove the end cap.
2. Remove the carbon brushes.
a. Remove the brush caps.
b. Remove the carbon brushes from the brush holders.
INSTALLING THE NEW CARBON BRUSHES
3. Install the carbon brushes.
a. Install the new carbon brushes into the brush holders.
b. Compress the brush springs into the brush holders and align the metal contact wings with the slots on the brush holders.
c. Secure the carbon brushes with the brush caps.
REASSEMBLING THE UNIT
4. Reinstall the end cap.
a. Install the end cap.
b. Secure the end cap with the (2) screws.