Couple Brushes Starter Motor Fiat 500 FLR 126 High Quality Era
The brushes have the task of transmitting voltage to the rotor, which in turn changes polarity.
They must be of a resistant material but not more than the collector where they work, to avoid damaging the armature (much more expensive).
They are pushed by a spring, they must adhere perfectly to the rotating part, therefore the more they are worn, the more the spring changes tension, you will notice when it is hard to start.
They have been built with quality materials to improve their performance.
To replace them, once placed on the bench it is necessary to remove the rear plate and replace them with a screwdriver. It is recommended to clean the part where they work well.
Below is a video on a complete maintenance which also includes the replacement of the brushes.
https://youtu.be/EvIBJf7Qy_0