Out of interest having read this post, and if identifiable problems appear to point to the bevel box (at present, this isn't entirely the case so it appears), a suitable third party for inspection purposes, could be Nova Racing Transmissions, partridge Green West Sussex. Nova are a small business specialising in gearboxes and final drives etc, somewhat similar to Quaife. They make a reversing gearbox similar to Quaife, that both Triking and I use.
Martin Ford-Dunne is the big cheese there.
