From the blog "Samurai Appliance Repair Man's Blog"

So, you go to open the door on your GE Spacesaver microwave and the handle comes right off in your hand! What's a brutha to do? Well, bro, you have two choices: replace just the door handle or replace the entire door. Replacing the door is obvious and easy but costs six times more than replacing just the handle. And while the handle alone is a relatively inexpensive part, it can be a tricky endeavor for the neophyte. Sublime Master RegUS_PatOff tiptoes us through these tulips. Part link