Diagnosis
Perceived timer inaccuracy. The brush uses a fixed internal timer, not an audio cue. The sensation is often due to brush head age or pressure.
How to Fix It
Time it objectively. Activate the brush and use a separate stopwatch. The motor will run for 2 minutes total, pausing briefly every 30 seconds as a tactile cue. Confirm it matches.
If That Didn't Work
A deeply drained battery can affect motor consistency and the timing circuit. Replace the AAA battery even if the brush still vibrates weakly.
Heads Up
The pause is a momentary stop in vibration, not a change in pattern or sound. It is subtle. Applying too much pressure can muffle the sensation of the pause.