Product review (5 stars): Perfect fit for Whirlpool Duet HT - Installation instructions in review.
Hinge fits in Whirlpool Duet HT model WFW9400SW04. See pic showing where original hinge broke. Pretty sure it was a manufacturer defect as the old hinge never worked as smoothly as this new one. New hinge is great!

To remove the hinge, you need a six pointed Star T20 bit. It's usually available in "Security Bit Sets". You can buy at Amazon or other hardware stores. Mine was from Harbor Freight item #68457.

Suggested steps to replace the hinge:
1. Spray WD-40 on the 2 hinge screws attached to the washer (see pic) and wait about 2 minutes.
2. Remove these 2 screws using a Star T20 bit. The washer door will not fall off as the hinge has two hooks on the back holding it to the washer.
3. After removing the 2 screws, lift the door and hinge assembly about half an inch up to unhook, and pull away from the washer.
4. Lay the door / hinge on a flat surface with screws facing up.
5. Spray WD-40 on the 8 screws nearest the hinge highlighted in the pic. Wait about 2 minutes.
6. Remove these 8 screws using a Star T20 bit. On the Whirlpool Duet HT, this was enough to allow the hinge to slide off the door. Didn't need to remove the other screws near the door handle.
7. Insert the new handle, align the holes, and reinstall the 8 screws. Do not fully tighten screws until all 8 screws are on so you can adjust alignment if needed.
8. Hang door / hinge onto washer using hooks on back of hinge. Reinstall the 2 remaining screws. Again, do not fully tighten until both screws are on.

JOB DONE!