Hi, we order a piece that was missing listed as the cap fill, but we can’t seem to get it to fit in. This is the ser. # for the dishwasher MD728438 B
and this is the part # of the item they sent us GEH WD12X10284.
Thanks Tiffany
Here is what comes up at AppliancePartsPros. The part number you provided does seem correct. The picture will let you com[pare it to what you received.
Note: Each square is 1 inch.
AP4390010
Check the dispenser itself could be that the threads in the dispenser are broken or perhaps a piece of your old cap is jammed in there.
Think it’s the threads as I don’t see them or anything else to keep the cap in. Would that mean we woud have to replace the door?
No, not the door but you would have to replace the dispenser
AP4368045
How do I get it out? I have taken the interior off but I can’t get it out. I don’t want to break something I may need.
Cancel that I got it out Thanks so much, now I just need to order the new piece.
I ordered a new piece AP2039187. But when I took the inside panel off and close the door it fell back open anD a small spring fell out and I have no idea where it goes? Please help 
This may help
http://www.applianceaid.com/soap-door.html#ge_closed