Review on 🔧 Neutop 3 Sets Bristle and Flexible Beater Brush Set Replacement for iRobot Roomba 600-700 Series: 614, 618, 620, 621, 630, 635, 640, 645, 650, 652, 655, 660, 665, 670, 671, 675, 680, 690, 692, 694, 695, 760, 770, 780, 790. by Renee Hackbarth

Put them in the Roomba 690. About a week later, I noticed that he occasionally emits a high-pitched short moan while running (maybe he got it right). far away, but I didn't notice it). At first I thought Roomba was dirty. I blew it out with compressed air and cleaned it as usual. Still groans sometimes. I then moved on to cleaning the brush assembly and even cleaning and re-lubricating the gearbox (which needed it anyway - phew). STILL piercing moans while running. I then ran it without the brushes and the noise was gone so I removed the yellow ends from these brushes and noticed that they were very tight compared to other brushes I had bought as part of a replacement set. So I used the yellow ends of the brushes to add some white lithium grease to the exposed metal spindles, snapped the yellow ends back on, lowered the brushes and the groan was gone. All in all a good buy - better than buying full sets of things I don't really need as the filter can be cleaned with compressed air and the side brushes don't need to be replaced as often as roller brushes.