Instant Pot DUO NOVA Series User Manual page 25

Pressure Control Features
Anti-Block Shield
The Steam Release Valve includes an Anti-Block Shield located on the
underside of the lid.
The Anti-Block Shield prevents food particles from entering the Steam
Release Valve and affecting the performance of the cooker.
Remove by pressing firmly against the side of the Anti-Block Shield
(pressing towards outside edge of lid) until it pops off of the spring tabs.
Clean and inspect the Anti-Block Shield after each use.
Reinstall the Anti-Block Shield by centering it over the spring tabs and
pressing down firmly until it snaps into place.
Do not attempt to operate the pressure cooker without the Anti-Block
Shield installed.
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