The Hipp toggle closes the main contacts as the pendulum arc drops below the trigger point. The huge electromagnets are energised. Lifting the rocking armature with its impulsing roller. The upward pressure is maintained as the roller runs along dead face and then around the corner of the pallet. The Hipp toggle can be clearly seen in its action in the V-block before and during the impulse.
I have a piece of tough material trapped between the electromagnet cores and the armature to reduce the noise. There was once a rubber tap washer beneath the domed adjustment screw head but it has been lost or worn away. I fitted these to stop the loud clonk as the heavy armature lifted and dropped back against the cast main frame before and after the impulse.