hmmm ...it is frustrating to say the least and I can sympathize with you.
I have a glass enclosure partial screen top....so humidity is always an issue. (but the hubby is building my racks so yea). Anyways....I have had perfect sheds the last 4 times with my babies....all of them.
move water to warm side
get an extra hide with sprayed down moss (just for the shed cycle)
keep the graded part of the top of the cage covered with aluminum foil
Keep the other glass side covered with a hand towel.
When in shed spray down the cage 3 times a day. (or whenever you see the humidity drop
I don't handle after the blue period
and....
If you have a piece of wood in there it helps to take it out and wet it down and place it back in. That will also create a lot of humdidty.
All of this worked for me with my balls....I know nothing in regards to corns.