Hi Joe! I have a case yellow handled cv sodbuster jr. that was exactly the same. I did exactly what you did, and got exactly the same results.
What I did next was to wrap the blade in a shop towel, lightly grip the blade in the jaws of the vise, and apply sideways pressure on the handle, first one way then the other, until it loosened it up a bit. And I didn't get it right on the first try, either - back to blade wobble. Squeezed the pivot pin on the corners of the jaws of the vase again - blade wobble gone, but too tight to open. Repeat sideways blade pressure.
I probably did this about 4 or 5 times until I got it to where I could live with it - no wobble and it opens and closes with an acceptable amount of effort.
I guess the main point I'm trying to convey is that these case sodbusters are a pretty tough knife and will take the abuse shown above without falling apart. I was a little hesitant to keep tightening & loosening for fear I would permanently damage the knife, but at least in my case it turned out OK. I figured it was an inexpensive knife and if I ruined it I would chalk it up to "live and learn". Your mileage may vary, of course.
There will probably be other, better ideas that come along here. Good luck and let us know how you make out!