I am so sorry! It appears that the original picture that I had up in the OP has disappeared.
Here is the picture: https://www.dropbox.com/s/ggbftaetioytchq/retention%20plate.bmp
When this happened to me, I was so confused with how to put back together the retention plate. I actually was able to fix it without buying new parts, but tragically I could not remember how to explain it for the life of me. But, the picture helped.
Let me know if you still can't figure it out, and I will do my best to help!
Can you explain this? I get the pin goes through the center but where does the spring and the nut go?