First, get a cardboard box that can fit over the winch and allow working room around the winch. Cut a hole in the bottom of the box and place it over the winch before you take the first piece apart. This will give you a chance at not losing any of the almost irreplaceable parts overboard. I am guessing from the boat's age that you have Maxwell winches.. Attached is an old Maxwell instruction book ..
Take pictures with cell phone or camera so you can see how it goes back together.. Good Luck !