DING, DING, DING, we have a winner!
I gotta tell ya, with all my experience working on farm equipment, I really doubted that the vise trick could put that much more leverage on the sprocket than a 1/2" drive breaker bar with 2' of pipe. Boy was I wrong! I put it in the vise like you recommended, bared down on it and nothing happened. I didn't hear any spokes twang or break so I figured I still wasn't turning hard enough. This time I really let it go. Figured what do I have to loose at this point, and it broke loose.
Now I can get in there and repack those bearings......
Thanks again guys,
Frank