The new part was shipped promptly and the only problem was that they failed to enclose instructions for re-assembly that were promised. A friend helped me install it. Good thing - he's taller and stronger than I am, and it helps to have an extra set of hands.
To disassemble, we just kept taking out screws till we had the fan off and the outside casing off. Even took off the door but that wasn't necessary. Be sure to remember the sequence of taking things off and keep the correct screws with each part - they're different sizes and types. Two screws require a special driver with a hole in the middle. (Not sure what this is called - the outside is a star shape. Can you tell I'm not a tool expert?
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Once you have the whole thing disassembled, you'll see the bracket where the nylon part connects behind the latch button by looking through the side. It's a little tricky to get the new piece on because of the shape. We had to slightly bend a metal piece in the middle of the plate behind the latch to clear a protruding piece in the middle of the nylon part. Then, after installing the part, reach in with a flat blade screwdriver to bend the metal piece back in place. That keeps the part from moving sideways. This will (hopefully) make sense when you try the 'operation.' We found it helped to spray a little silicone on the latch release inside where the new part activates opening the door, and also on the edges of the external button to make sure everything moves smoothly without sticking or hanging up.
Now that everything's back together, it works great. It's nice to have the oven back in working order, but I've lost a very good excuse for not cooking.
Good luck!