You can get the catalog pdf from the mfr webpage http://shared.whirlpoolcorp.com/assets/pdfs/literature/Repair%20Part%20List%20-%208186458.pdf
or look up the part number on appliancepartspros.com and it will show you the exploded view. Mfr webpage has all the revisions.

yours P/N look like
16 4452396 RH (For SS MDL) heavy spring 4451009 medium weight
17 4452395 Spring,Torsion LH lightweight spring.

Alternately you if you keep breaking the LH (lightweight spring) you can replace both springs with the 4451009 medium weight spring which is used on several models which don't offer the aluminum door (Meteorite) option which is why they have two RH springs in your production line. (to reduce parts on the production line)

UPDATE: I found out that if you put a drop of motor oil or other same weight oil on all the places where the spring goes through a metal hole or rubs on (when spring is new), that the spring will no longer break every year! Mine has lasted 5 years now without a change.

GO TO START OF 2ND PAGE (POST #12 FOR PICTURES)

1. unplug the unit
2. you need a Phillips screw drivers medium and large.
3. Open door and hold onto the handle at all times firmly and remove two screws on the inside of the door near the top that are in recesses in the plastic door frame inner.
4. Pull door handle outward away from the hinge ends and it will come loose from the brackets at the bottom. Put door outer somewhere safe.
5. close remaining door attached to oven after you have removed the two screws you just took out.
6. remove 4 screws from the vent at the bottom of the microwave and remove the vent.
7. Remove the two screws under vent that hold the microwave to the oven frame. They go through the brackets marked #4 on the diagram.
8. Wiggle out the microwave just far enough to clear the screw on the bottom of the door that is blocked by the oven vent. (about 1 inch)
9. Remove two screws from bottom of microwave door that hold on the plastic door frame marked #2 on the diagram.
10. Open the door carefully.
11. You can now remove the Plastic door frame #2
12. Close the door again.
13. The torsion springs (whats left of them) are at the bottom and criss cross attaching to the left and right Door hinge.
14. I don't have any pictures but the springs are identical just one has the end with most bends at the left and the other has the most bends at the right. Hopefully only one broke so you can see how it goes through the hinges. Just put the other one on exactly opposite.
15. At the center where the springs intersect, put a baggy tie rap to hold the two springs together lightly or use aluminum speed tape. This stabilizes the springs and helps not to damage the door next time they break.
16. Good Luck :)

Pictures now at post #12

Your welcome, Today I added more info above after I have talked to many people. Your model has the lightweight RH spring and heavy LH spring. If you have problems again and the lightweight spring (or heavy) keeps breaking you can switch both to a medium spring weight.

Well after days of talking with Kitchenaid and Whirlpool this door spring problem is huge. You should tie the two springs together with a tie rap because when they break they almost always break the outer door assy glass, which is over $150 bucks to replace.

All these Kitchenaid Whirlpool models have the same design problems.

Now on to the above mentioned microwave door problem. They have known they have a problem with the spring breaking from within 3 months to at max limit is about 3 years. When they break they most often hit the outer glass which breaks then or later after heat cycling. They have changed the spring number several times over the years and models and the stainless exterior finish models the most. Lots of different tensions and models due to the stainless door is heavier and the brushed aluminum door models is lighter with the white,black and bisket colors being different again.



on a side note,
Trying to get more options out of the same amp draw (for home upgrades without rewiring for higher amp circuit) The oven broiler is very low powered. They try to do a sales rename to make it sound positive by calling it "closed door broiling" but in fact if you broil with low temp with the door closed its NOT broiling but in fact a boiling affect not even a roast or bake which brings out a liver taste in the meat. You also don't get crispy fat and can never get a rare cook.

I replaced a torsion spring 4452396 in a KitchenAid microwave. It lasted for about a year. Has anyone tried what is described as a heavier torsion spring?

Well my new spring lasted almost exactly one year then broke again. Called Kitchen Aid and told them im on my 4th spring. Seems to break about at 6000 door openings. I average about 20 door openings a day.

They seem to think the right spring is too thick thats why it keeps failing. They said instead of using the one thick 4452396 (right) and one thin 4452395 (left) to replace both with the medium strength spring which is in they parts book as 4451009, it is cheaper also.

They said they would send me them free since I have had so many problems with them.

When I get the new parts I will take pictures and post how the springs go on.

Good stuff, evo! Made it a "sticky".