Good advice so far. It's not a monumental task, but one that takes some skill and the right tools. I've repaired a few with about that amount of damage, and they're still going strong 10+ years later. Some, I just did an acid wash to get the surface crud off, and left it alone, knowing that some day I'd have to possibly replace the board. If I were you, I'd go this route before immediately replacing the board. Take it off, give it a good ZEP/vinegar wash and scrub, and see if it fixes the problems. You might get lucky and get some serviceable time out of it. But it may fail again in the future, but you won't be any worse off if your plan was to replace it anyway. If you think you want to salvage it, and have it permanently repaired, then i would send it off for repair.