Pulling it off dry can potentially injure the eye if it is stuck hard. My advice is to get the skin soft by either putting in the moss box as FR said or soaking the snake in tepid water until the eye cap feels more flexible. Giving the snake the opportunity to handle it itself is always the best 1st approach. Since kings love to hide in a box of moss, the solution is pretty easy. I think the New Zealand moss is the best, but any sphagnum moss will suffice.