Designers initials missing?

When I looked at the reverse of this 1983 penny, I thought there were no initials. A closer look, I can see something, but not sure what. Any ideas?

 

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on the 1st photo you can see a faint FG.most likely a grease or clogged die

 

With the lines in the last picture, it could be that the die was polished, and they were ground off.