Lambretta DUE50 Owner's Manual page 22

CONTROLS AND GAUGES
Handlebar Lock
To lock, turn the handlebar to the left, then turn the key from "OFF" to "LOCK" while pushing in
on the key. If the lock does not engage, move the handlebar slightly to the right.
To unlock, turn the key to the "OFF" or "ON" position.
Note: Always lock the handlebar and remove the key before leaving the vehicle unattended to
prevent theft.