I just tried it and it worked.
1. Go to the PNR page for your reservation. This is the page that lists all your flights, seat assignments, etc.
2. Open a new browser tab and put the following in the URL field:
https://www.aa.com/reservation/print...raryReceipt.do
I suggest you copy it to a Notepad or other plain text editor, remove any bogus carriage returns, then save the file for future use.
That should take you to the ticket receipt for the trip you have open in your other browser window.
It worked just great for me a few minutes ago.
Edited to add: I see the forum software changed the full address to a truncated clickable link. Right-click, then "Copy Link Address". Once the entire link address is in your clipboard, paste that into the plain text editor, then save.