the oscillation on my vu5670 has gotten super slow and jerky, sometimes it just stops swinging.

Diagnosis

The jerky or stalling oscillation on the Rowenta VU5670 Turbo Silence is almost always caused by the degradation of the synthetic lubricant within the oscillation gearbox. Because the VU5670 utilizes a high-torque motor for its "Turbo" settings, the oscillation mechanism is under constant mechanical stress. Over time, the factory-applied grease mixes with ambient household dust and pet hair, creating a thick, abrasive paste that increases friction. When the grease becomes "gummy," the worm gear cannot smoothly drive the main oscillation gear. This results in the "stuttering" motion you see, where the fan hesitates before jumping forward. If the friction becomes too great, the motor's internal thermal protection may kick in or the plastic gears may slip, causing the oscillation to stop entirely. You can confirm this by turning the fan off and trying to gently push the fan head left and right; if you feel a "gritty" resistance or a physical catch, the gearbox is contaminated.

How to Fix It

To restore smooth movement, you must perform a deep clean and re-lubrication of the gear assembly.

1. Unplug the unit from the wall outlet to ensure total electrical isolation.
2. Lay the fan on its back on a soft surface to prevent scratching the chassis.
3. Locate the black plastic housing at the base of the motor neck. Remove the three Phillips-head screws securing the oscillation cover.
4. Carefully lift the cover to expose the white nylon gear assembly. Do not pull the assembly away from the motor shaft too aggressively, as you may dislodge the synchronization pin.
5. Using a cotton swab dipped in 90% isopropyl alcohol, scrub away all the old, darkened, or crusty grease from the worm gear (the small spiral gear) and the larger drive gear. Ensure the teeth are completely clear of debris.
6. Apply a small amount of high-quality white lithium grease or a synthetic PTFE-based lubricant to the gear teeth. Avoid using WD-40, as it is a solvent, not a long-term lubricant, and will cause the problem to return within weeks.
7. Manually rotate the gear several times by hand to ensure the grease is evenly distributed across the mating surfaces.
8. Reinstall the black plastic cover and tighten the screws firmly, but do not over-torque them, as the plastic housing can crack.

If That Didn't Work

• Check for gear tooth wear. Inspect the white nylon gears for any "shaved" plastic or missing teeth. If a tooth has snapped off, the fan will jerk every time that specific gap hits the drive gear. In this case, the gear assembly must be replaced as a single unit.
• Inspect the oscillation clutch pin. Ensure the pin connecting the motor shaft to the oscillation arm hasn't slipped or worn down. If there is excessive "play" or wobbling in the shaft, the pin may be worn, causing the timing to be off.
• Verify the oscillation knob functionality. On the VU5670, the oscillation is engaged by a physical pull-knob. If the internal spring or plastic catch of the knob is broken, it may only be partially engaging the gear, leading to intermittent stops.
• Test for motor fatigue. If the fan oscillates fine on low speed but stalls on "Turbo," the motor may be overheating, causing the plastic components to expand and bind. Ensure the motor vents are clear of dust using compressed air.

Heads Up

• Never use silicone spray or oil-based lubricants (like 3-in-1 oil) on these gears; they can degrade the white nylon plastic over time, making the gears brittle.
• Perform this lubrication maintenance once every two years if the fan is used daily during the summer to prevent permanent gear stripping.
• When cleaning with isopropyl alcohol, ensure the gears are completely dry before applying new grease, as alcohol can interfere with the adhesion of the lubricant.
• Always ensure the fan head is centered before tightening the housing screws to avoid putting lateral tension on the oscillation arm.