Many thanks for your suggestion Tony, but I'm afraid I don't understand how that can help with my issue.
Allow me to explain my point of view: on a 2014 AI, the plastic mast support tube and the V braces are both essentially anchored through to the X-bar at the top (so cannot move independently of each other at the top). The bottom of the V braces sit
on top of the plastic mast brace and so also can't move independently of the mast support, meaning the V braces can't extend the depth of the mast support to relieve the tension in the hull floor (as I see it). Does my argument make any sense?
If the V braces acted directly on the hull floor I can see how they could push it down, but as it is the only solution that springs to mind to effectively make the mast support deeper and so relieve the strain on the hull stud area (due to it being pulled up to meet the mast support) is the one I mentioned of inserting washers between the underside of the mast support and the stud support area in the hull floor
Happy to be corrected if I'm wrong!