Demagnatize cartridge??

My Denon 304 seems to have been "magnatized" by a new stylus force gauge I am using -- the gauge just "sucked" the cartridge down to it. Now the cartridge magnetic attraction. Does anyone know if this is harmful to the cartridge or playback? Is it possible to de-magnify a cartridge? There is also an excessive amount of "hum" coming through, even though I have tried different loading configurations. Could these problems be related? I appreciate your help!