Replaced the defrost bi-metal and all is well (except the ice maker still isn't working but will figure that out shortly.) Checked online and fell upon this awesome website which gave probabilities of what the problem was and how to fix it. Part arrived less than 24 hours after I ordered it, magically. Completely satisfied!!
PS, the actual replacement of the part is relatively easy. Much of the 2+ hours consisted of getting the food out of the freezer, and melting the ice, removing the shields, etc.