I have an old Plano plastic tackle box that I am trying to clean up. It has these places on the underside of the lid. I’ve tried a few different things to clean it up to no avail. This box has been stored in attic and in unheated area for 25 plus years. Any guess as to what it is and how to clean it?
This is likely caused by soft baits eating the plastics. Older plastics weren't made to resist the solvents that make soft baits soft and squishy.