@Richardadelberg check out Desmond’s site - I believe he has a section describing these medallions. http://omega-constellation-collectors.blogspot.com/
It is quite hard to take it off and much harder to put it back on (without the help of glue). Are you sure you have the right one for replacement? Because looks like this medallion is correct for Constellation C case only.
I've not seen the back of a medallion - so don't know if that is what they should look like. The observatory looks ok as does the star arrangement (for a particular era) but its the textured background that I noticed. Since this is the later iteration of the medallion, I thought the same - what Connie is the OP intending to put this on? As wells C-cases the observatory/star style could also fit with 168.010/0.16/.018 etc but I think that particular textured background looks more like even later references like the 168.0048 shown in Desmond's blog