DIAGNOSIS Debris (toothpaste, mineral deposits) is on the magnetic charging contacts, creating a slippery barrier that breaks the magnetic hold.
FIX Unplug the charger. Use a cotton swab dipped in a little white vinegar or rubbing alcohol to scrub the circular metal contact ring on the charger base and the corresponding flat spot on the back of the handle. Dry completely.
IF THAT DIDN'T WORK The silicone pad around the charger base can become deformed or greasy. Clean it with soap and water and ensure it's completely dry. A warped pad prevents the handle from sitting flush.
HEADS UP Never charge the handle when it's wet. Water droplets magnify the repelling effect of the magnets. Always dry the back of the handle before placing it on the charger.