My watch the vibrator (maybe also by the quickfit band) sound very bad. The last day... I had see one Apple watch and the vibrator was very very soft and efective... the FR935 vibrator is as one diesel engine and the Apple Watch as BMW 6 cylindrer in line... For the price Garmin should mount a vibrator of best quality...
This is normal in all watches or my unit is broken?... I don´t know...