Richard J Kinch wrote:
Therefore, I want to know how it was installed in the first place.

Usual method is just sheet metal screws through cleats on the cooler to the
plywood deck.

I see. This means if I unscrew and re-screw a couple times, the screws
will eventually lose the grip. I may need to bed the screw holes with
epoxy to strengthen them when I mount the seat back on the deck.

Now I know what I will up against. Thanks.

Jay Chan