i'd recommend contacting Neil and seeing if he will send you a bezel - while your at it, see if you can get one for me, mine came smudged
you can also buy inserts on ebay - but, there is no guarantee it will fit and may need to be filed.
Personally, i have not had luck - in getting bezels from the same dealer that worked - silix sent me the wrong UPO bezel, then sent me new bezels - but, it wouldn't snap in - it was very close to fitting, but didn't fit like the orig
my solution was to glue it - then cover it with rubberbands so the bezel held in place until the guerrilla glue set
Had to chip off some excess glue with a razor - and unless you were looking at it from less than 2 inches away, you couldn't tell. if you put it right up to your eye you could notice that it wasn't set as flush as it should be