Replace the brush roller when bristles are bent or broken, not on a calendar.

Six to twelve months is typical, but you should inspect it every month. The real answer depends on your floors, how much pet hair you have, and how often you run the thing.

Hard floors wear brushes slower than carpet. Carpet (especially high-pile) shreds them faster. A house with two dogs will chew through a brush in half the time of a clean, pet-free apartment.

Don’t overthink it. Pop the brush out once a month, spin it, look at the bristles. If they’re frayed, bent permanently, or missing chunks: replace. Same if the brush doesn’t spin freely or you see grooves worn into the rubber or plastic. A worn brush means worse pickup, more noise, and your robot working harder.

A new brush roller is usually $10–20. That’s cheap compared to burning out the motor or