The Roomba adjusts its brush assembly to effectively clean many types of floors (carpet, rugs, tile, etc.). The way iRobot pulled it off was by having a mechanism within the main brush assembly that adjusts the height with a cable. The more resistance the main brush has the higher the brush assembly will lift off the floor and vice versa.
The cable develops a slack when the Roomba is idle and it tightens when the main brush motor turns on. The slapping of a cable that is not anchored will sooner or later lead to the tear of the brass end. You end up with a useless Cleaning Head Module with a broken off brass end.
So to make sure you save this cable you will need to do the following:
- Remove the bottom cover by removing the four screws
- Remove the Cleaning Head Module by removing the screws from the chasis
- Inspect the condition of the "Red Dot" sticker
- Replace or re-enforce the "Red Dot" with stronger adhesive tape (duct, all weather, etc.)
- Test your work by pushing the cable upwards to see if it pushes the tape out. Fix if needed.
- Re-assemble everything in reverse
This tip will prolong the life of your Roomba 500 series robot so it can continue cleaning your floors.