You might want to try and lower that humidity. 50-60 is a good range. 70 is a little high and you might run into problems with upper respiratory infections. The temps need to be bumped up a bit too. Around 92 on the hot side and 82 on the cool side. You may want to invest in a thermostat to help regulate your temps. Keep them constant! Here's a link to MGReptiles, he's the one to ask any heating and thermostat questions! www.mgreptiles.com/Herpheat.html
My only other question is how old/big is your snake. If you have a young snake, it may be stressed in a big old tank. If you need to keep him in it put LOTS of crumpled up newspaper and many many hides. There is also the caresheet from this site which should help you out too....
http://www.ball-pythons.net/modules....warticle&id=52
Hope this helps.....Good luck!