Thank you Sam L. for the info. Since posting the question I've discovered how to remove the sheaves at the base of the mast. First, remove the stainless steel set screw from the stainless sheave plate (about 1.5x1in). Since the mast base is aluminum the screw will likely break off at the head. No problem though. Easy to tap out. Anyway, just pull on the sheave plate with pliers and the sheave plate slips out freeing the sheaves. They may fall inward but the base isn't deep enough to lose them. Poke your longest finger (ha) up to the top and forward side of the mast and you should feel the wiring harness. From there you can do any number of things such as string a messenager using an electrical fish tape, etc., from the steaming or anchor lite. Yes, lots of fun..... You have to poke the fish tape forward to get it down into the compression post, from there to the base of the post and out to the bilge to the DC panel. Have fun! (Sometimes I think these guys in the yards do this sort of thing on purpose to get a good laugh after work swafing down a few brews!)