My pump is a Whale 8MKIII. West Marine has a maintenance kit for this pump that has valve flappers and bellows.
If you decide to put your wooden handrailings back on, long #10 machine screws can be alittle hard to find. Jamestown Distributors 800/423-0030 carries 5" #10-24 18-8 SS machine screws. They also sell long boards for fairing hulls.