Have you ever used the optional side fins on your GO board?
If you have, perhaps you used regular length footstrap screws to mount the
If so, then you may have "punched out" the back/bottom of the side fin mounting
The side fins mount with 25 mm long screws where the std. footstrap screws are 28 mm long.
Something else to check.
Use the cooling of the evening to "pull" your sealing compound down into all those footstrap and side fin insert holes, even the ones that have never had a screw in them.
If you put a little dab of the sealer in the screw hole and nothing happens, you will know that that particular screw hole isn't a problem.
The hole (s) that draw the sealing compound in will be the ones that really need to be sealed.
Hope this helps,