Hi thanks for the question.
Please send me the complete model number so I can help you better.
Remove that screen and look for this part .Its in the middle and it unscrews, If its dirty or worn could cause the problem.Also clean in front of the door where it meets the tub It gets dirty at that location and can cause the problem as well.
Is this what you have. You looked at 506.
Those pieces you found in there could cause the problem your having.And that part I sent you is not for your model
If you still have the problem , Look in front of the door where it meets the tub.It gets dirty at that location.If it is dirty clean that out.
Its not a replacement of the d/w you need ,Just clean it out And if the previous owners were clean you woud not have crumbs. Use this product it works great I think thats all you need .
In front of the door wher it meets the tub when the door is closed.
And that water is ok It should be there.
Ita very good for that problem.
Thanks and Good luck