Cleaning, sanding, then anti-seize spray sounds like the plan. I turned the boat back over this afternoon, will start putting it all back together tomorrow.
Thanks to all for starting me in right direction.

i didn't consider the aluminum expanding / distorting due to the 240 pound load placed on the very thin wall tubing.
In the future, I'll look for the 3/4" steel pins, I don't see them binding or seizing.