Cover Nikon Cameras

Cover Nikon Cameras
sticky dirt stuck in the plastic back cover of my camera. Mild soap clean didn't work. How I can delete?

The camera is a Nikon F80 Slr Camera with a back cover that allows the printing date. The cover is made of plastic, probably some kind of thermoplastics. I have no idea what the sticky is in the camera or what is just (went there after my sister used the camera). It looks and feels like dirt that leaves sticky stickers on certain surfaces after taking off the sticker. I tried cleaning with a mild soap solution, but not very useful. They only way I know of the disposal of the substance is slowly and laboriously scraped to one side and then pinch it off but it takes a long time and no matter how hard you try not always going to be some dirt left over. Please help. Thank you very much!

nail polish remover is lowered sticky dirt without rubbing.

Just messing around with my new camera