Take out the two 8mm screws fastening the hinges in place.

Remove the hinges. They are not identical so keep track of which is which.

Quick hinge stiffness fix:

Place the hinge in a vice but do not tighten it down.

Rest the hinge on the bottom sheet metal without gripping the metal pin. The locking washer should be facing upwards.

Tap the top of the metal pin with a hammer to loosen up the hinge action.

If you loosen the hinge too much, take it out of the vice and place it on top of the vice. put a small hex driver over the top and tap it with a hammer to drive the locking washer back down.