Finishing my first stringer job-- taking my time so hopefully don't have to do it again! Mine were in really bad shape like you say yours are. One thing that really helped me was to leave one side in the boat and try to measure and copy from it for the other side with the exception of notching the outside stringers. Think that was a major mistake from supra. Learned from a bunch of others posts on here that adding the drainage holes to at bottom of stringers is a must and will make them last longer. i spent most of my time shaping/sanding the bottom of the main stringers to the curvature of the hull before bedding them to avoid hard spots. Its definitely not a perfect job by any means, but I've got to think it's better than was from the factory! Good luck with your project.