I'm going to say this again...
If the eye caps are messed with by using any object or tape to try to remove them, you can remove the cap that is under the one that gets shed off. This secondary cap is needed and the snakes eye can shrivel up if it's removed.
Another member took her snake to the vet who attempted to remove stuck caps. It obviously was not a stuck cap because the vet removed the necessary eye cap and the snake went blind.
Even if the outer caps are shed, the new caps can and will become dented or dull if humidity is too low. This can give the illusion of stuck outer caps.
Raise the humidity. High.
Very high! And keep it that way. Cover the lid completely. Make a humid hide. Get a hydrometer and be sure the humidity is about 70% at all times. This should fix the problem.
I have a pastel that has never shed well. His humidity must be 70-75% at all times or he just doesn't shed well. Some are like that. Don't mess with the eyes.