RE: Removing Fin
Yes, rub some soap on your fin before you install it.
Then install it normally, but take it back out again and check where
the soap has turned dark and shiny vs where it's still dull like when you
rubbed it on.
Take a smooth (single cut) file and work off the dark shiny spots.
Actually, this is the way a Tuttle fin is supposed to fit, nice and snug and you need to work it down into the fin box and back out again at the end of the day, but not so tight that it cracks the paint.
Just rubbing some soap on the fin root will "lubricate" it so it's significantly easier to push your fin in and to get it back out again.
Actually, to get your tight fitting fins out of a Tuttle box, it's best to use a rubber mallet or dead blow hammer.
Smack the fin lightly toward the back of the board after removing your fin screws and the fin should come out with just a little back and forth (front to back here) rocking to loosen it.
Do not file or sand the sides of your Tuttle fin root down until the fin just
"drops" into the finbox. That is too loose and the fin looses a significant
amount of it's rigidness (side to side) if you fit the fin too loosely in the fin box.
Hope this helps,