I have the same posts under the clear plastics on my FG as well. I couldnt find any new ones so I gently wriggled them side to side until they came out of the original plastic then i buffed them up and resued them on the new plastics. I used a set of needle nose plyers to squeeze in the top of the post (the bit which looks to have been pressed over by a rivet press) which goes through the clear plastic. They will still hold on tight and once the screw goes through there not going anywhere anyway.
