That's normally caused by one thing. The pinion nut backing off and it's pretty common. I've chucked a few up in a lathe before and turned them out just to make um "look nice" again, but it's totally unnecessary. Let her rip.
I found the pinion gear has some wear, including this worst part (see previous post above with latest photos).
The thread for this post kind of ran it's course so was trying to bring attention to this. I'm hoping I can just go with it. The ring gear looks great.
To everyone who replied, thanks for all the advice.