I have a 1982 25' ft swing-keel and have been curious about the swing-keel bolt. From what I've read, it should last a long time without replacement or problem. But, I'd like to inspect it just to be sure. Is there a way to do this? Should it be replaced? when? Also would there be some indication if there is a problem (vibration, sound, etc.) to warn me or will it just drop off the boat and the boat sink of course. Thanks!