I have a 1998 Evinrude 200 hp (carburetor not FICHT). It runs great in forward gear and idles nicely in neutral. However, when I shift into reverse, the engine bucks and makes clunking noises. I'm in the northeast and boat is in winter storage. I would like to get the problem solved before I put it back in the water. I'm new at this so I won't be doing the repairs myself. What are the possible causes? If I don't do anything will the problem get bigger and more costly? I've read other posts and people mention a clutch dog. What is this? Is it expensive to replace/repair? Help (thanks).