After multiple replacements of the Elixir 9" version and no other vents available in that size I opted to redesign the whole thing, since the Elixir is really a piece of junk.
The solution was to make the fan opening into a skylight and install one of those round fans which I think are found in Casitas, Olivers, etc. Two acrylic panels, the top slightly bronzed, with some maple trim and some much tougher stuff on top, with two coats of epoxy clearcoat in the mix before Interlux Brightside topcoats. I did go to some lengths to make the thing waterproof and so far it is working well. The new fan is quite good and can be left open in the rain with no leakage.
The big dividend is that the light
is great and I don't worry about leaving the fan cover open, considering my limited memory and attention span.