Just thought of this...
I think it was last year I read on the Graybanded Kingsnake Forum that one guy has this problem a lot with his graybands so if I remember right this guy said he would keep the egg bound snake in a Rubbermaid tub with water (1 to 2" at about 80F for a few days and I think he said the snakes always pass the eggs(I'm sure timing has a lot to do with it…don’t wait too long). Don't quote me on this but I'm pretty sure that’s all he did(maybe go back a few years and look that up(June or July most likely). I might try that next time I run into an egg bound issue.