Before you remove a brake rotor from a hub, you should:

Marking the position of the rotor before removal is crucial for several reasons. It helps ensure proper alignment when reinstalling the rotor, which can be particularly important in systems that rely on specific positioning for effective functionality. Misalignment can lead to brake performance issues, such as uneven wear or compromised braking efficiency.

When you mark the rotor's position on the hub, you create a reference point to maintain the same orientation during reinstallation. This is especially relevant in vehicles with specific designs or configurations that might require the rotor to be installed in a particular way.

While inspecting the caliper, cleaning the hub area, and checking brake fluid levels are important parts of brake maintenance, these steps do not directly address the need for rotor alignment. Each of those tasks serves a distinct purpose in the broader context of brake service, but they do not contribute to ensuring the rotor is put back correctly on the hub, which the marking process helps to accomplish.