my crosswave is making a horrible grinding noise, sounds like it's eating rocks

Diagnosis

The "grinding rocks" sound in a Bissell CrossWave 1785A is almost always caused by a mechanical obstruction trapped between the brush roll and the internal drive housing, or a failure of the brush roll bearings. When a hard object—such as a pebble, a stray screw, or a piece of plastic—gets wedged into the gap between the rotating brush and the plastic chassis, the motor continues to force the rotation, causing the bristles or the roll itself to scrape violently against the interior casing. Alternatively, if no debris is present, the noise is often the result of "bearing burnout." The ends of the brush roll rely on plastic end caps and bearings to spin smoothly. If water or thick cleaning solution penetrates the bearing housing, it strips the lubrication, causing the plastic to grind against the metal drive shaft. You can confirm this by removing the brush roll and attempting to spin it manually; if you hear a high-pitched screech or feel a "catch" in the rotation, the bearing has failed. If the noise only occurs when the machine is powered on, it is likely a debris jam or a stripped drive gear.

How to Fix It

Follow these precise steps to clear the obstruction and restore the drive system:

1. Power down the unit and disconnect the power cord from the wall outlet. This is critical to prevent the motor from engaging while your fingers are near the brush.
2. Tip the CrossWave onto its rear wheels to expose the underside of the cleaning head.
3. Locate the brush roll release mechanism. Depending on your specific sub-model of the 1785A, you will either pull a release tab or unscrew the brush roll retainer.
4. Slide the brush roll completely out of the housing. Do not just poke at it; remove it entirely to inspect the "track" where the roll sits.
5. Inspect the drive gear (the small toothed wheel at the end of the motor shaft). Check for any chipped teeth or wrapped hair/string that may be creating friction. Use a pair of needle-nose pliers to remove any hair tightly wound around the shaft.
6. Check the brush roll end caps. If you see black plastic shavings or "dust" around the bearings, the roll is worn out and needs replacement.
7. Clear any debris from the suction intake path located directly behind the brush roll. Small rocks often migrate from the brush into the intake throat, creating a rattling sound.
8. Reinsert the brush roll, ensuring it clicks firmly into the drive gear. Test the rotation by spinning it manually with your hand before plugging the machine back in.

If That Didn't Work

• Replace the Brush Roll (Part #206022): If the grinding persists despite clearing debris, the internal bearings of the brush roll have likely collapsed. Replace the roll with a genuine Bissell multi-surface brush. Even a small warp in the brush roll shaft can cause it to vibrate and grind against the housing at high RPMs.
• Inspect the Drive Belt: If the noise sounds like a high-pitched squeal combined with a grind, the drive belt may be slipping or partially frayed. Remove the bottom plate of the cleaning head to inspect the belt for "glazing" or stretching. A worn belt will slip on the pulley, creating a harsh mechanical noise.
• Clean the Suction Motor Impeller: If the grinding sound is coming from the top of the machine rather than the floor head, a hard object has likely bypassed the filter and entered the vacuum motor impeller. This requires a full teardown of the motor housing to remove the debris. If the motor smells like burning plastic during the grinding, shut it off immediately.
• Check the Wheel Casters: Occasionally, a pebble becomes lodged in the front swivel wheels. Because the vibration travels through the plastic chassis, it can sound like the motor is grinding. Spin each wheel manually to ensure they rotate 360 degrees without resistance.

Heads Up

• Avoid Over-Saturating: Never use excessive water or non-approved detergents, as these can seep into the brush roll bearings and accelerate the grinding wear.
• Pre-Sweep Large Debris: The CrossWave is designed for "wet-dry" messes, but it is not a shop-vac. Large pebbles, metal screws, or heavy gravel should be swept up first to prevent damage to the drive gear.
• Regular Hair Removal: Once a month, use a pair of scissors to cut hair and threads off the brush roll. Accumulated hair puts extra torque on the motor, which can lead to premature gear failure.
• Check the Filter: Ensure the dirty water tank filter is clean. A clogged filter increases backpressure, which can cause the motor to run hotter and make the internal components more prone to vibration noise.