Safety first: Allow the cooker to cool and depressurize before opening.

Clean contact surfaces: Thoroughly clean the lid sealing surface and the top rim of the inner pot.
Inspect sealing ring: Remove the ring and check for cuts, flattening, or hardening. Replace with a genuine Polaris sealing ring if any damage is found.
Correct installation: Refit the ring evenly in its groove, ensuring it is not twisted.
Test with water: Run a pressure cycle with water only to confirm that leakage is resolved.

Steam or water leaking around the lid during pressure cooking; cooker struggles to reach pressure.

Possible Causes