my nes510 makes a horrible screeching or grinding noise when it runs, sounds like metal on metal.

Diagnosis

The high-pitched screeching or metal-on-metal grinding noise in the Eureka Flash NES510 typically stems from one of two failure points: the brush roll end-caps or the main motor impeller. Because this model is designed for lightweight agility, it uses plastic bushings and thin bearings that are highly susceptible to "hair-binding." When long hair or synthetic fibers wrap around the brush roll, they create friction that melts the plastic housing or forces the metal axle to rub directly against the chassis, creating that piercing screech. If the noise persists even when the vacuum is running without the floor nozzle attached, the issue has migrated to the motor assembly. This is usually caused by a foreign object (like a small pebble or hard plastic shard) bypassing the filters and entering the motor fan housing. Once a piece of debris hits the high-RPM impeller blades, it creates an unbalanced vibration and a grinding sound as the blade strikes the internal plastic casing. You can confirm this by removing the nozzle; if the sound vanishes, the brush roll is the culprit. If the sound remains, the motor is compromised.

How to Fix It

To resolve the noise and restore the unit, follow these precise steps:

1. Disconnect the power cord from the wall outlet immediately to prevent motor burnout.
2. Detach the floor nozzle from the main wand. Flip the nozzle over to expose the underside.
3. Locate the brush roll locking tabs. Use a pair of needle-nose pliers or a blunt screwdriver to release the brush roll from its seated position.
4. Slide the brush roll out of the housing. Inspect the two end-caps (the circular plastic pieces on the sides of the roll). Look for melted plastic or blackened areas where the axle meets the bearing.
5. Use a pair of heavy-duty scissors or a seam ripper to cut away every single strand of hair and thread wrapped around the axle. Ensure the axle spins freely by hand with zero resistance.
6. Clean the interior of the nozzle housing using a damp microfiber cloth to remove any grit or debris that may be causing the friction.
7. Reinsert the brush roll, ensuring it clicks firmly into the locking tabs. If the axle is worn down to the metal, apply a tiny drop of silicone-based lubricant to the bearing points.
8. Reattach the nozzle to the wand and power on the unit to verify the noise has ceased.

If That Didn't Work

• Inspect the Motor Impeller: If the noise persists without the nozzle, remove the rear filter housing. Use a flashlight to look into the motor intake. If you see a piece of debris lodged in the fan blades, use a long pair of tweezers or a vacuum hose (from a different machine) to suck the debris out. Do not poke metal objects into the motor as you may bend the impeller blades.
• Replace the Brush Roll Assembly: If the end-caps are melted or the metal axle is visibly bent, cleaning will not fix the screeching. You will need to replace the entire brush roll assembly. Ensure the replacement part matches the NES510 specifications to avoid fitment issues that cause further grinding.
• Check the Hose Gaskets: Occasionally, a high-pitched whistle can sound like a screech if there is a hairline crack in the flexible hose. Run your hand along the length of the hose while the machine is on; if you feel air escaping or the pitch changes when you squeeze a certain section, the hose needs replacement.
• Motor Bearing Failure: If the grinding is accompanied by a burning smell, the internal motor bearings have failed. This is a non-serviceable part of the NES510 motor assembly. In this case, the entire motor unit must be swapped out for a new OEM replacement.

Heads Up

• Avoid Wet Debris: Never vacuum damp carpets or spilled liquids. Moisture enters the motor housing and causes the metal components to rust, which leads to the permanent grinding noise you are experiencing.
• Weekly Maintenance: Make it a habit to clear the brush roll every two weeks. The NES510's lightweight design means it cannot handle the torque of a heavily wrapped brush roll without overheating.
• Filter Integrity: Always ensure your filters are seated perfectly. A loose filter allows dust and pebbles to enter the motor fan, which is the primary cause of internal metal-on-metal grinding.
• Avoid Over-Lubrication: If you lubricate the bearings, use silicone oil only. Avoid WD-40 or heavy grease, as these attract dust and hair, creating a "grinding paste" that wears down the plastic housing faster.