When should I replace my robot vacuum's brush roller?

Replace the brush roller when bristles are bent, frayed, or broken — not on a fixed schedule. Inspect it monthly; typical life is six to twelve months, but it varies by floor type, pet hair, and usage. Hard floors wear brushes slower than carpet, and homes with pets need replacements more often. A worn brush reduces pickup, increases noise, and strains the motor, so swap it for $10–20 when you see damage or grooves.