What year?
If your boat is an 85 or newer, there is a phillips head machine screw (3/8") that is accessable from under the toe rail. Easily done in a dingy, but can be acccomplished on deck a little more uncomfortably. I don't know how to tighten the older models, but can check next weekend and get back to you. There are several older models on my dock I can check with the owners. Gene
