I have a 376 that has leaked for the past 5 years since I have owned it. I tried what I thought was everything.... For maintenance we had our mast pulled this year and while it is off I have removed the mast step. I found the issue, the caulk that was bedded under the mast step top plate had failed and water intrusion was obvious. So I will clean that up and use a better solution when I reinstall the step. If you look at the mast step there is almost no way water should come in, the wire path is 3" above the deck and if the screw holes (4) are properly sealed the only intrusion possible would be water running down the wires and through the wire path, although possible it should be very little.
This did damage the table which I stripped and refinished last winter (caution, the laminate is very thin, don't sand too much). The flooring was also damaged and replaced from years of leaking before I owned it. If you can't solve the leak, the best solution I had was to tie a small towel to the mast to absorb the water and change it from time to time. Not a great solution but did save the floor and table from more damage.
Good luck!