I have several AMF Alcort Sailboards, Tiga, sailboards that were retired by a MN Boy Scout camp in the mid-90s. I believe they have the word "one" repeated on the bow several times. I am trying to remove / salvage the mast foot attachments from one of the hulls. I do not see any hardware fasteners. I have rotated the plastic units from the top and bottom of the hull without any success in removal. Please let me know how to remove the units.