Why Won't My Roomba s9 Side Brush Spin?
- Hair wrapped around the side-brush post
- Debris jammed under the brush
- Side-brush screw over- or under-tightened
Problem Description
Your Roomba s9 side brush is not spinning during cleaning. Remove the side brush by pulling it straight off the post on the bottom of the robot. Inspect the brush arms and the post for tangled hair, thread, or debris. Clean the brush motor gear area. If the brush spins freely by hand but not during cleaning, the motor or gear may need replacement.
Why This Happens in Real Homes
The s9's single side brush sweeps debris from edges and corners into the robot's path, and it stops turning when hair wraps tightly around its mounting post or debris jams the gear underneath. Since the s9's shape relies on that brush for corners, a stuck one shows up as dirty edges.
Unscrew and lift off the side brush, then clear the hair wound around the post and clean any debris from the gear area beneath it before reinstalling with the screw properly snug (not stripped). A brush that's bent or splayed should be replaced. If a clean, freely-mounted brush still won't spin during a clean, the side-brush motor needs iRobot service.
Symptoms
- s9 side brush not spinning
- Corners left dirty
- Side brush motionless
- Grinding at the brush
- Brush spins weakly
- Recurs after cleaning
- Brush bent or deformed
- Edge cleaning poor
Recognize these? Here's what usually causes it.
Common Causes
- Hair wrapped around the side-brush post
- Debris jammed under the brush
- Side-brush screw over- or under-tightened
- Bent or worn side brush
- Gunk in the brush motor or gear
- Brush not seated on the post
- Side-brush motor fault
- Carpet fibers binding it
Most fixes happen in the first 3 steps.
Keep small objects, loose cables, and thin rugs with fringe off the floor before running the vacuum. These can tangle in the brush roll and damage the motor. Do not use the vacuum to pick up liquids, sharp objects, or fine construction dust as this can permanently damage internal components.
Tools & Requirements
Step-by-Step Solution
Remove and inspect the side brush
Flip the Roomba s9 upside down. The side brush is the 3-arm spinning brush on the front-right corner. Pull the brush straight up off the post — it lifts off without tools. Inspect the brush arms: bent or frayed bristles reduce sweeping effectiveness. Check the post for hair wrapped around the base. Hair tangles are the most common cause of a stuck side brush. Pull off any wrapped hair or thread with your fingers or scissors.
Clear the side brush motor housing
With the side brush removed, look at the post and surrounding area. Debris can get into the motor housing and jam the brush motor. Use compressed air to blow out dust and fine debris from the brush post hole. If you see visible debris packed around the post, use tweezers to pull it out. Spin the post with your fingers — it should rotate freely. If it is stiff or stuck, debris is inside the motor housing.
Check for the side brush error in the app
The iRobot Home app shows specific error codes. If the s9 detects a side brush motor stall, the app shows an error like 'Side brush is stuck' or error 18. This error triggers when the motor draws too much current (jammed) or too little current (disconnected). After cleaning the brush post, clear the error by pressing Clean on the robot. Start a new cleaning session to test.
Replace a worn side brush
The s9 side brush wears out over 6-8 months with regular use. Signs of a worn brush: bristles are permanently bent flat, arms are cracked or broken, or the brush wobbles on the post. iRobot sells replacement 3-arm side brushes (compatible with the s9, s9+, and j7 series). Press the new brush onto the post until it clicks into place. The brush should sit flush and spin freely when tapped.
Test the side brush motor
If the brush spins freely by hand but does not spin during cleaning: the motor may have failed. Start a cleaning session and watch the side brush. It should start spinning as the robot begins to clean. If the main brush rolls and the vacuum runs but the side brush does not move: the side brush motor is likely burned out. Contact iRobot support for a motor replacement — the s9 has a 1-year warranty (2 years if registered). Motor replacement requires disassembly of the bottom plate.
Quick Solutions
Still having issues? This is usually the deeper cause below.
If this comes back after following these steps, check whether a recent app or firmware update reset a default setting — the fix works, but the setting gets reverted silently.
["Side brushes last 6-12 months", "Check monthly for hair tangles", "Replacement brushes sold in packs"]
This issue almost always looks more complex than it is — the majority of cases trace back to a single setting, a stale credential, or a default that shipped wrong.
- Hair wrapped around the side-brush post
- Debris jammed under the brush
- Side-brush screw over- or under-tightened
- Bent or worn side brush
- Gunk in the brush motor or gear
Before you go — try one of these (they fix most cases).
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Official Manufacturer Manual
iRobot provides official product documentation through their online manual rather than downloadable PDF. Access setup guides, troubleshooting steps, and product specifications for your iRobot Roomba s9.
Source: homesupport.irobot.com
Need More Help? iRobot Support
Note: The contact information below connects you directly to iRobot's official customer support team, not Trunetto. They can help with warranty claims, device replacements, and advanced technical issues.
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