To change your power tool carbon brush, in most cases you can easily access them behind carbon brush caps or a screwed plate which reveals the brush holder and the brushes in those holders.
Some brushes are held in place with coil springs that need to be lifted up with a screwdriver to release the tension and then you can pull the worn brush out.
The following is an image of a spring to help show you what it looks like:
You can purchase replacement carbon brushes from us here, where we can get the perfect brush for your model of power tool.