Botvac 85 Loud brush noise

[thbrewst]

I have a Botvac 85. When the vac comes off the charging station to clean it is relatively quiet, like when new, but as soon as the brush motors turn on there is a fairly loud 'whining' noise. Based on other threads I assumed it was the side brush belt so I replaced it, but the noise is still there. What else should I try?

- Based on other threads it seems unlikely that the main brush belt would be broken.

- The main brush still spins so the motor is working, how would I know if it needs replacement?

- Similar with the side brush motor. Plus on visual inspection when I changed the belt it did not appear overly worn.

To further note; when the vac is out and goes back to charge, and hence turns the brushes off, the noise goes away again.

Many thanks for the assistance.

>>Forgot to add that I also replaced the bearing on the main brush. And when that didn't work I also replaced the entire main brush with a new one.

[thbrewst]

So, I dismantled the Botvac again today and disconnected the motor for the side-brush. the noise is gone. So I assume I just need to buy a new side brush motor as I do not see any obvious external issues with the current one.