If the defrost timer on your fridge is a mechanical timer (works like a wall clock, and ticks annoyingly), then sometime or the other you’ll have this thing fail on you. Ours did, but I wanted to be sure it couldn’t be saved, so I decided to pry it open. It isn’t easy to open the timer up. You’ll inadvertently break a tab or two (I broke one), and you’ll have to be careful opening it up, because as soon as you pop it open all the parts fly into the air. One, you’ll have to search all over the room for parts. Two, because you’ve no idea what the parts are, you’ll never know if you should stop searching for more parts. Third, when you do gather all parts and try to put it back in, you’ll have no idea which part goes where.
I scourged the Internet for a close-up picture of any defrost timer to help me put all the gears and parts back in, but I found nothing.
So, to help some people who might be in a similar situation, I post these pictures of my defrost timer and I hope it helps you put things back in the way they were. When I put all the parts back in, my timer started ticking again. I’ve no idea what fixed it, but the ritual of opening and putting everything back in seems to have worked. Click on the pictures for a full view.