I have never removed the bow backrests from my 255 but will need to in the near future for the same reason. Inside the port side head compartment in my boat, there appears to be some plugs in the forward bulkhead. My guess is that there are screws under those plugs. Inside the helm compartment, I found some screws also in the forward bulkhead which I assume are holding the seat backs in place. When you figure this out please report back.