Thomas, FWIW I have a mac 1993c different boat. The way I understand it there's a liner underneath the top of the boat which probaby prevents you from reaching it from underneath. If it's like my boat, the cleat is mounted on top of your starboard combing. To access this on my boat you would have to cut in a hole beneath the cleat to access that area. This is accomplished by finding a appropriate size deck hatch which you can find on this site and others. Basically you cut a 4-8 inch circular hole (depending on the size of the deck hatch you purchase) to access below the cleat, replace your cleat, perhaps add additional backing plate, when you are done, you fit the outer mounting ring of the deck hatch in the hole and close it with the deck hatch. Hope this helps a little. I'm sure there are people here who have made this repair and will chime in.