Shed Aid....meh. Your numbers don't ad up, which leads me to believe your humidity gauge is off. If you have a hot side (floor temps) of 90 and a cold of 80, then your ambient temperature should be around 85 degrees, not 75 degrees. BTW 75 is to low for ambient temp, 85 is a great ambient goal. This tells me that you have to much air escaping, which would also mean your humidity is probably not as high as you think. Humidity readers are notoriously off. Can i see a picture of your setup and what are you using to read your temps and humidity? finding the correct balance between these 4 items (hot side floor, cool side floor, ambient, humidity) is a dance that can take time to get right. My racks have a hot side of 91, cool of 79, ambient of 85, humidity of 60-65.

Now as for the stuck bits of shed. fill up your sink with water a bit warmer than luke warm. hold your snake and put him in it while still holding him. he will try to cruise around and may even dunk his head under, which is fine. just let him keep running his body through your grip and the stuck pieces of shed will loosen and pull off. Do not grab the shed and pull, let him control the pace at which he rubs it off. This can take 5-15min.