Diagnosis
Accumulation of toothpaste, saliva, and minerals between the handle's metal hygiene ring and the plastic body.
How to Fix It
Use the included travel cover's tip or a soft-bristled brush. Gently pry under the metal ring to lift it away from the handle. Clean the exposed groove and the underside of the ring with water and a mild soap. Rinse and dry thoroughly before snapping the ring back into place.
If That Didn't Work
For mineral deposits, use a cotton swab dipped in white vinegar. Apply only to the affected groove, not the electronic components. Wipe clean with a water-dampened swab after a minute.
Heads Up
Do not submerge the handle or run it under water while the metal ring is removed. The seal is compromised, and water can enter the battery compartment.