Can't open Inspection Port/Hatch

Hi Folks

Just wondering whether anyone had any suggestions on how to open an inspection port which is on very tight? At first, I thought it was me being a weakling, however a few friends have also tried, and the hatch covers are stuck tight. Is there a tool that anyone can recommend to open these things? ... they're not the easiest thing to get a grip on with your hands/fingers.

Many thanks in advance guys.

PS. This my first post, so apologies if I've submitted in the wrong place etc.