New shaft bushings are pressed in. This is the brush end cap with four brush holders getting a new bushing. Each has a spring retainer to hold its brush against the armature slipper. The drive housing (other end) also gets a new bushing. Bushings get a dose of molybdenum grease, which handles high temperatures quite well. Don't overdo the grease; use just enough to provide a lubrication wedge without getting all over the starter brushes and slipper.