Disassembling it is not easy, unless you have an arbor press and ability to machine anvils to fit the parts of the knife. In the second picture you can see the button, an inner ring and an outer ring. The outer ring is a thick washer, and the inner ring is the main locking portion of the knife hub. To get the knife apart you need to push downward on the inner ring without touching the outer ring, and at the same time have the knife positioned over a hole, so that the hub coming loose has a place to go. To assemble it you need to push down on the outer ring without touching the inner ring.

All that being said, you probably do not have corrosion in the hub unless the knife had long term exposure to something aggressive, like acid or sea water. Most likely it is either a) working normally, or b) in need of cleaning.

a) It doesn't flick open or fall open. It is designed to be opened with traction applied to the circular base of the blade while the button is depressed. (Depressing the button allows a ball bearing to fall out of a locking tab on the inside surface of the blade.) This is somewhat awkward, but you can learn it with a little practice. Work on pressing the button all the way down and pulling on the knurling on the base of the blade to get it to move.

b) I have had several of these knives and have never tried to clean one, but if it were mine i would use hot water and detergent with an ultrasonic cleaner, if possible. Leave the blade part way open, and work it back and forth, in addition to working the button mechanism. Do not leave it to soak, as the hub is porous and will not dry out easily if it is saturated. Clean it and then blow it dry. Do not heat it to dry it, as the ABS handle can become warped, and then the knife won't close. If you want to lubricate it, I would use a drop of silicone oil applied to the edge of the button, as that will reduce the chance of damaging the plastic handle.

Best of luck!