Diagnosis
The iRobot Roomba 694 uses a single rotating side brush (the "edge-sweeper") that is secured by a small, specialized screw. When this brush falls off, it is rarely a case of the brush simply "slipping out"; it almost always indicates that the retaining screw has either vibrated loose over time or has completely fallen out due to the high-torque rotation of the motor. If the brush feels like it won't "seat" correctly, it is likely because the internal drive spindle is obstructed. The root cause is typically a buildup of compacted hair, pet fur, and grit inside the brush mounting hole. Because the side brush is the first point of contact with debris, hair wraps around the base of the stem, creating a physical shim that prevents the brush from sitting flush against the chassis. If you try to force the brush on without clearing this debris, you will either strip the screw threads or put undue stress on the small motor, leading to a "Side Brush Error" on the iRobot Home App.
How to Fix It
To properly reinstall the side brush and ensure it doesn't fly off during the next cleaning cycle, follow these precise steps:
- Inspect the Hardware: Locate the side brush and the small Phillips-head screw. If the screw is missing, you cannot simply "push" the brush on; it will fall off again within minutes. You will need a replacement screw specifically designed for the 600-series chassis.
- Clear the Spindle: Use a pair of tweezers or a needle to dig into the hole where the brush attaches. Remove any hair, carpet fibers, or dust clumps wrapped around the drive peg. The peg must be completely clean and visible.
- Align the Stem: Take the side brush and align the hollow center of the brush stem with the drive peg. Gently press down. You should feel a distinct "click" or a flat seating sensation. If the brush wobbles or sits at an angle, there is still debris in the hole.
- Secure the Screw: Place the screw into the center hole of the brush. Using a small #0 or #1 Phillips head screwdriver, turn the screw clockwise. Tighten it until it is snug, but do not over-torque it, as the plastic housing can strip easily.
- Test Rotation: Gently flick the brush with your finger to ensure it spins freely 360 degrees without hitting the robot's plastic bumper or chassis.
If That Didn't Work
- Check for a Bent Spindle: If the brush won't sit flat even after cleaning, inspect the metal drive peg. If it is bent at an angle, the brush will never seat correctly. This usually happens if the Roomba ran over a heavy object while the brush was jammed. In this case, the internal side-brush motor assembly must be replaced.
- Replace the Brush Head: If the plastic center of the brush is cracked or warped, it will not grip the spindle. Replace the brush with a genuine iRobot replacement part. Generic third-party brushes often have slightly different tolerances and may not fit the 694 spindle perfectly.
- Inspect the Screw Threads: If the screw spins indefinitely without tightening, the threads in the plastic housing are stripped. You can attempt to fix this by inserting a tiny sliver of a toothpick or a small piece of Teflon tape into the hole to provide more grip for the screw.
- Reset the Sensor: If the brush is physically secure but the vacuum reports a "Side Brush Error," perform a soft reset by holding the CLEAN button for 10 seconds until the light ring flashes.
Heads Up
- Weekly Maintenance: Every two weeks, unscrew the side brush and remove the hair wrap from the spindle to prevent the screw from vibrating loose.
- Avoid Over-tightening: The chassis is plastic; applying too much pressure with the screwdriver will strip the mounting hole, making it impossible to secure the brush.
- Genuine Parts: Always use high-quality replacement brushes. Cheap clones often have thinner stems that wear down quickly, leading to more frequent detachments.
- Debris Check: If you notice the brush is "flicking" debris away from the vacuum instead of toward the center, check if the bristles are worn down or bent; if so, replace the brush immediately to maintain cleaning efficiency.