Static discharge, even at zero attenuation, can do all kinds of funky things. Time for the for the isolation drill. Presuming you have checked another input source and it's OK, change out the armwand to the one that you knew (last time anyway) that worked properly. No hum? Reinstall the questionable combo. Hum? Start disconnecting leads one-at-a-time beginning at the cartridge while remembering to turn off the rest of the gear in-between.
Good luck & happy listening!
Good luck & happy listening!