Microwave oven door heavy

This appears to be an Australian model and these are the only spares I can find. They do sell the latches. If the hinges are damaged and causing this, you will feel movement. Looks like it is time for a new one.

https://spares.bigwarehouse.com.au/index.php?cPath=46427_53341_57047

https://www.google.com/search?q=sharp+R-9X56+replacement+hinges

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take off the top vent cover , should be three screws ...hang the door provided nothing is broken off the door or the microwave.. after hanging put the vent cover back on. If your model has a little clip/postage size at the top hinge or if you think there is something missing at that location you may need that to keep the door from coming back off... It can be bought on line if your model needs it. some do and some don't if you found something near that area before the door fell off... then your model had one..

In your owner's manual (available free online here) this is called the "microwave inlet cover".

See the tag in your oven cooking cavity or near the door frame for your full model number.

The cover is located in the ceiling of the oven.

You should be able to remove and clean or replace the cover without removing the oven from the wall.

The oven installation instructions and parts list are also on that page.

You can also find handy exploded views and order any needed parts and accessories by model or part number here.

We're happy to help you with free advice and we'd appreciate your thoughtful rating of our answer.

I cannot determine from your description what part it is you exactly need.
This is a link to Sears Parts and you make and model
Look through the diagrams.
As for price and delivery... that's up to Sears
Good luck!

http://www.searspartsdirect.com/partsdirect/part-model/Kitchenaid-Parts/Microwave-Parts/Model-YKHMS1850SS0/0593/0123370?searchedModel=YKHMS1850SS&blt=

Check and replace as needed the door switches/catches.

Check for a shorted lamp. When you open the door, often they turn on the light.

Another thing is look for wiring being scrapped by door hinges.

If your oven door has gotten bent or warped (maybe you rested something heavy on it…), you need to remove the door, disassemble it, and straighten it. You can lift most oven doors off of their hinges by opening the door several inches to its first "stop," and lifting the entire door straight up.

If the hinges have become worn, damaged, or bent, you probably need to replace them. We recommend replacing both hinges at the same time, to prevent uneven wear of the undamaged hinge.

See answer here http://www.fixya.com/support/t265705-microwave_door

in different thread.. Basically have to pry plastic trim ring off inside of door with putty knife (careful, it cracks easily) to get to screws on bottom of door. See second pic. Top screws are easily accessible from inside of door. Spring can easily be replaced by hand once you get adequate access. You'll need a fairly stubby right angle screwdriver (I used a cut-down #2 Phillips bit and small Vice-Grips as a make-do) to get to the screws. Also need Torx (T10, I think) to detach the shock absorber doodads from the door where they attach above the hinges. If you're just starting to take the door apart, be careful when you take out the top 2 screws on the inside-- they hold the inside plastic piece on , but they also hold the whole outer stainless/ glass/ handle piece on. It just slips in at the bottom, so be ready to slide it out when you take these screws out.

That would be the service manual. You could contact Kichenaid for that, but I doubt the manual's necessary just yet:
http://www.kitchenaid.com/custserv/service.jsp

You can find helpful exploded views of this model here: http://tinyurl.com/gv383

Unless you're replacing the entire door for some reason (what an expense!) then it's not recommended that you remove the door. If so, you'll have to carefully mark the hinges and the door to be sure you get it back in exact alignment. Otherwise, you'll have a chance of microwave leakage.

Instead, the door panels should be taken apart and then you can remove only the panels and parts that are needed.

In most cases, there is a choke cover on the inside surface that needs to be carefully pried apart, and that will allow access to the hidden screws, as the sample drawing shows.

Usually the exploded view is all that's needed, but if you nned more help, the service manual is the next step.

I would suspect a couple of wires are crossed.

GE puts mini-manuals in their units, which have wiring diagrams, schematics, etc. Very handy.

It will be folded up in a small envelope, usually behind the control panel or hidden elsewhere. That should help you.