How do I replace the side brush on a Xiaomi or Roborock robot vacuum?

Regarding the Roborock: Unscrew the single Phillips-head screw under the brush, pull off the worn one, line up the new three-pronged brush, and screw it back in. It’s a five-minute job—no technician needed. Just check your model number to ensure compatibility, and cheap knockoffs work fine if you replace them a bit more often.