I have severe ice forming in my freezer.

are you sure its condensation and not water flowing over the top due to being unlevel, or pan cracked

have you cleaned the bottom of the freezer from dust that gets under there so it can breathe

Hello.
I can help. Once we notice anything different from before we start becoming more aware of small variations. Regarding things on the top shelf warmer than on the bottom, this is always true because, "warm air rises and cold air falls". If you want the top shelf colder turn the thermostat to the next colder setting, always a good idea in the Summer season anyway.

Even though your gasket looks good, a ten year old gasket is not as pliable as a new one resulting in the moisture problem you describe. I would begin by applying a thin coating of vaseline to the gasket once a week for a month. This little trick of the trade will often work. If it doesn't improve the situation do replace the gasket.

Ice cubes freeze from the outside, so the center of the cube is the last to freeze. Ice is pure water, only H 2 O, so as the ice cube freezes, all of the dissolved minerals are pushed to the center. Near the end of the freezing, there isn't much water left in the center of the cube, so these minerals become very concentrated, and they form the "white stuff" – the technical name is precipitate. The hardness minerals that cause the "white stuff" are not toxic.

The thickness probe should be approximatly 1/4 inch off of the evaporator.Sounds like you might have loose grids on the evaporator.turn the unit off and remove the curtain.use a flash light and inspect the grids.There should not be space in between the joints,if there is the ice will freeze behind the grids and not properly release when in harvest. Also gently pull at the grids,if they pull towards you or wiggle then they are separating. I have removed one of the grids and had the unit continue to run for sometime until the evaporator could be replaced.The plating being spotty causes release issues as well.Finally check the level of the machine,front to back and side to side.Not being level will also cause release problems

Something is holding your Ice Slab at the bottom from your description.
Some causes are
1 Dirty - scaled up evap, or just dirty w muddy covering,
2 the vacuum breaking holes are stopped up If it is making a sla whith the evaporator warm no ice take a flashlight and hold it where its shining to the back of the evap and look for the light on th cube forming slots next to the ones your shining the light into Upper corners of each hole must be open.
3 The slab is freezing uneve most like cause is a stopped up distributor tube at the top thats feeding the water down the evaporator.
4 On some models thay had a closer fitting water curtian (the cover in front of the slab) and the top of the sheet touched this and caused the slab to stay uprite and continue the "slide" forward.If your curtian is of the older style and has metal hooks on it with verticle slots n the curtian look at the slots and see if the slots are worn making the whole curtian slide down ward I have seen this several times.4B On some older models there is also a plactic coated wire diverter on the bottom infront of the evaporator. If the palstic coating is gone or the bottom or is not even, the slab could hang up there. 4C If you have the newer plastic pins make sure thay are seated in the mounting properly.
5 Nickel plating could be comming off (any copper color on the lower 1/3 of the evaporator?).
6 I have seen some of the horizontal plates them selves be loose and not in flush try pushing and pulling on them especially the ones at the bottom. ANy that are loose and comming out is your problem.
This lengthy extrapolation is by no means all of the possibilities but most of the common ones. If this helps you solve your proble please rate me accordingly. If it leads you to the correct and completed repair WOULDNT WE MAKE A TEAM?? And Good luck to you.

You said you checked the seal but one thing you can try to be double sure the seal is tight put a thin layer of vaseline along the entire seal it will fill in any gaps and you can be sure it is sealing completely.

IT SOUND LIKE YOU HAVE AN AIR LEAK IN TOP OF GASKET,THE GASKET HAS A MAGNET IN IT ,YOU CAN USE A HAIR DRYER TO SOFTEN THE RUBBER UP TO SEE IF YOU CAN GET THE SEAL BACK TIGHT,BE CAREFULL NOT TO BURN THE GASKET OR YOURSELF,THANKS-MIKE

someone suggested to me the other day to put weter foods closer to the top the ones with dripin water and more solids down at bottom they said this changes the climate inside to be more economical
im just passing this info cause ive never had or been in contact with a upright freezer

The reason for ice buildup is an air leak. Recheck all around the gasket by taking a dollar bill and closing the door on it and pulling it out. If you don't have resistance, you found your leak. Heat that area with a blow dryer to relax the gasket and close the door to let the magnet and seal set. Also, rub some vasoline on the hinge side gasket to keep it from dragging.