If I had to take a guess, I would say that the rivet on the back (or whatever it is) was used to cover the embossed manufacturers logo on the fly box.
The logo is located in the same place.
Also, I found a source for the clock lens.
It's one of those cheapie plastic clock inserts you find at arts and craft stores. (The kind that you stick inside those wood carved stands)
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I believe this is this is the correct size, but Im going to go to Joann Fabrics tomorrow to verify.