Detergent cup won't open

The detergent cup will not open. I can open it manually. The edge of the door seems to be a bit rough. Sometimes it appears to have opened sometime during the cycle because when I open to dishwasher the door is open and the packet of soap is only partially dissolved Other times the door doesn’t open at all.

Duplicated post. Replied here: http://forum.appliancepartspros.com/dishwasher-repair/745-kenmore-ultra-wash-not-dispensing-rinse-aid.html

Gene.