Our Sharp R-930CS-P sticks and is very hard to open, will open from the push button if you push it hard

Something must have spilled into the mechanism and dried there. You'll need to access and clean it out.

Your door open button or door open lever is worn or broken.

If your oven is mounted in a cubby type enclosure, you will have to remove the trim kit, slide it out partially, unplug it, then slide it completely out and set it on a table top to work on it.

The service manual has safety information, disassembly information, and parts information including parts numbers. I have uploaded it to my site here: http://www.microwavecontrol.com/R930cs_sm.pdf

You can order Sharp parts from Encompass here http://tinyurl.com/7qy85y
or Sears here http://goo.gl/zWz6Bz

Feel free to contact me via my Web site http://www.microwavecontrol.com if you need further assistance.