That one works
Now I'm wondering if there is some kind of gasket under the switch that works with the no-frost system
There is none. Power off first, pop out the switch and see if the insulation is wet or not. An over night defrosting and some new insulation pushed in around the switch area might be a good idea.
If I buy a new switch it doesn't look like it comes with any type of gasket just the switch
I don't know how you are getting water/moisture inside the divider