Catalina 25 Wiring
On my 1982 Catalina 25, the bow wiring light wire runs along the port side at the hull deck junction. It's secured with screwed wire ties, and while not the easiest things to get to, a short screwdriver and some patience will get them loose. However, it's one, continuous piece of wire, and thus not likely to break. I would look very carefully at the connections at the bulb holders and the panel, clean all contacts throughly, check your fuse and fuse holder; in other words, positively eliminate all other possible problems before condemning and replacing the wire. The easiest way to run replacement wire in the mast is to use the existing wire to pull the new wire through. If the existing wire is broken(unlikely), or if a new wire is to be run, drill your entrance and exit holes in the mast and lower a piece of small stuff(monofilament fishing line works well)with some weight on it down the mast and fish it out through the lower hole. It's a fiddley job, especially trying to catch the line inside the mast, but it's the only way I know to do it.