I recently bought a used board with FCS fins installed (the very common fins FCS M5 with the two bases, I dont know the exact name). However, the fin boxes look strange (see photo). Even though FCS fins do fit, I just broke 3 fins in 4 sessions. The fins always broke at the base. I didn't hit a rock or sandbar or anything. The fin just broke -- THREE TIMES now. So I figure there must be something wrong with the "fin box-fin-combination". I only know futures and FCS. What kind of fin system is that and can you recommend any solution for my problem? The photo is bad quality but the box seems to be too wide as the fins are very loose and just fixed by 4 screws.You can see the rest of the fin in the rear compartment.
Thanks a lot for any help, I like the board