Brush keeps going up and down

Take it to your local Sebo dealer for repair. Sounds like the servo has gone bad.

Hi Laura, it's Jack at Dyson

DC28's selector pad (located by the red on/off switch) allows you to select the correct height setting for the particular flooring you're cleaning. Patented Dyson Airmuscle technology will then raise or lower the rotating brush bar within the cleaner head to the correct level for optimum performance, or shut it off for cleaning bare floors or delicate rugs.


I hope this helps, but if you have any further questions or if you're having difficulty with your DC28, you're welcome to get in touch directly. You can reach our experts by emailing [email protected]

look for a blockage -something may have dislodged the lever mechanism, or be stuck preventing the roller or position leaver from moving.

There are (4) main components that affect the height adjustment on your vacuum. They are: Brush roller, Servo Motor, Control board, and Sensor pulley. You have eliminated two of the possibilities already. I would ask you if either of the height adjustment lights on the PC board come on, indicating that the board is attempting to raise or lower the vacuum. I would also have you inspect the Sensor Pulley. That is the yellow pulley that both belts connect to. Do the two sections of the Sensor turn easily without resistance? Do they spring back when released? Are the magnets (small black round magnets on the inside of the Sensor wheels) still in place? That Sensor pulley system tells the PC board whether or not the vacuum needs more or less resistance (to raise or lower the servo motor). Because the Sensor Pulley is completely mechanical (no electrical components); If this Sensor pulley is completely functional, your problem is likely the PC board. I have included some links to the PC board and Sensor pulley for your convenience. Hopefully this helps. 5465 Red Ring Windsor Sensor 86145060 5740 ER Computer Controller Windsor Sensor SR XP 86140160

Hello! The M085845 has an automatic height adjustment that cannot be manually changed. There is a roller lifter assembly that helps to raise and lower the nozzle depending on whether the vacuum is in the upright or reclined position. You do not have to make any adjustments to the vacuum when going from carpet to hard floors. The brushes will continue to spin at all times when the vacuum is in use. Hope this helps!

It's likely the circuit board that controls the height adjustment motor, or the motor itself. Your local sebo service center will be better able to test to see just what is wrong. Though it wouldn't hurt to take a look at the boards sometimes they're visibly burnt, or connections can be loose. Good Luck!

Sorry you've had to wait so long for a reply. Perhaps you no longer need help, but here goes anyway. Must confess I'm not certain about this, but my guess is that the automatic height adjust mechanism (let's call it the HAM for convenience) isn't working properly. The HAM works by sensing the drag of the brush roll against the carpet, and raising or lowering the front of the machine as necessary to maintain constant drag. So first you need to check the HAM, as follows: with the handle in the locked upright position, switch on and wait for a few seconds (there may or may not be any signal from the green UP or DOWN lights). Then, still switched on, lower the handle to the normal operating position and check that the green DOWN light comes on. Wait until the DOWN light goes off and then return the handle to fully upright (switched on all the time). When fully upright the UP light should come on for a few seconds and you may be able to see the handle tilt backwards as the front of the machine rises. If this is all working properly, we need to look elsewhere for a solution. The next thing I would look for is for a broken belt. Just turn the machine over while it's running and look to see that the brush is rotating (keeping fingers and clothing well clear, of course). Sebo belts usually last 15 years or more, but breakages are not unknown.
I realise this may not exactly solve your problem, but it should give you something to work on. If you need more help, post a reply here, saying what you've found so far, and I'll try to be more specific.
Good luck!

Make sure you're not trying to adjust w/ handle in upright locked position because thewre is a cam which raises the vacuum head a little bit when handle is locked in upright position. If this is not the problem, turn vacuum upside down with handle in unlocked position and power cord not plugged in(for safety reasons obviously), unscrew and remove 3 screws that hold belt/beater brush assembly cover in place(2 are in corner near ends of beater brush and 1 is towards motor housing) tilt end of cover with 1 screw up and remove cover(there are 2 tabs at beater brush end of cover). Right above this is the height adjustment assembly with 2 rollers, raise up the assembly gently and using your finger or a bristle bottle brush,etc. make sure there is no debris caught between the height assembly and the hose(you will understand when you see it), if there is no debris you can now see the pattern on the bottom of the height adjustment knob and the lobe that rides on it, just check to make sure nothing is broken and/or missing, hope this helps!!

Worst case scenario is that there's a fault on the circuit board, but another possibility is that the brush roll is not rotating freely. The automatic height adjustment works by sensing the drag on the brush roll, and altering the height to maintain constant drag. So, if the brush roll is sticking, the sensor detects the extra drag and raises the height accordingly. First thing to do, then, is remove the brush roll and remove any hair (the most common problem) or other stuff that may be wound round it - especially at the ends near the bearings. Check that the brush roll is able to rotate freely.
If this doesn't solve the problem, the next possibility is that a spring has broken in the clutch/sensor device where the two drive belts meet. That will cause the sensor to "think" there's more drag on the brush than there actually is, and hence to raise the height as before. This clutch (which isn't really a clutch) has two toothed pulley wheels - one driven by the belt from the motor, the other driving the brush roll. Holding one wheel stationary, the other can be rotated slightly and there should be increasing resistance to that rotation. If the spring has broken there will be no resistance until you reach the limit stop. Unfortunately, if you've no experience of these units, it can be really difficult to know whether one is broken or not! The third possibility - failed circuit board - is, in my experience, the least likely. These are typically extremely reliable, and will usually last the life of the machine (25 years or more). I've never known one fail, but it's always possible.
I hope this helps. Any questions, just post here again and I'll do what I can. Please remember to rate this response. Thanks!

Raise the height adjustment to it's highest setting.Turn the belt lifter knob on the brushead counterclockwise till it stops.Remove the brushead,then turn the belt lifter clockwise till it stops,releasing the belt.Turn the brushead around to the back.You will see 2 latches holding the brush plate assembly on.Unlatch those,and remove the brushroll assembly.Remove the brushroll from the plate by bending the tabs at one end to release the brush.Remove the old belt,and slide the new one over the brushroll.If you remove the entire brushroll,install it with the screw heads facing the floor.The ends of the brush roll have different size caps,one end is larger than the other,and one is black,one is white.This is so the brush will only go in one way.
Re-install brushroll assembly,latch it down.Look thru the opening in the back,and turn the belt lifter till you see the hook pick up the belt.Install the entire brushead on the front of the vacuum,and lock it down,then turn the belt lifter to drop the belt onto the shaft.Lower the height adjustment,and you are ready to go.