I have a new Brinsea 190 and started it to check on temp, humidity etc. All looks good but now BUT now I need to add eggs and cannot figure out how to get the trays to go flat. When you turn the turning off the shelves jut stay at the angle they are at and you can't get to them to ad the eggs. The shelves need to be horizontal. I am sure it is easy, just don't know how. Can anyone help??