I have a Roomba 630. Recently it started just spinning its brushes intermittently. It occurs in a regular pattern: spinning them for half a second, then nothing for about 1 second, spin again, etc. It does this even when the brush and roller are removed. It also makes a “chunking” noise in time with this activity, and moves the underside portion where the brusher/roller go every time it chunks.
I took a couple videos here. Note that the weird turning and putting its butt up in the air only happens when the brushes and vacuum bin are removed. At one point, after messing with it trying to find the problem, I put it back together and it worked normally for a little while. Then this started again.
The problem appears to be the smaller metal bearing ring. It does not move freely and I can feel something grinding when I force it. Do you sell a replacement? If not, do you know the part number?
Unfortunately, we do not sell replacements for this part. We would suggest you to purchase a cleaning head for Roomba. You can purchase this on the manufacturer’s website.