After PMing ED, he suggested that I run op_test_inputs. It seems my right nub is definitely dead
However, the left nub is working perfectly according to the test page. The blue icon moves around smoothly at a consistent speed. The numbers show up yellow (which I believe means they're ok) so I don't know what's up with the diagonals :/ Calibration in the applications? It's very strange because no matter what values I change in the Mupen plugin config file, nothing changes the diagonals