The fins technically have two jobs.
They are supposed to help keep the pump loaded and they are also there to ensure the boat stays somewhat straight on an unplanned shut down.
What Intake do you have? I have a couple here if you need one, is yours rounded or flat (delta pad or round keel)... let me know. They aren't too tough to replace, it's mostly about how bad you want to change it.
I need to see which ones I have left.
GT