Hiya @Pdiddy32 and welcome to CoinTalk. Here is a place you can read about and see examples of what can be found on coins. In fact there is a photograph of a coin a little like your coin with the 'missing L' about a third down the page. http://www.error-ref.com/?s=die grease
I would go with die deterioration damage. If it was grease, the distance between the vertical part of the L would be much further away from the "I" ( the length of the horizontal part of the L). IMO. Jim