you really shouldn't use a demagnetizer. Many cartridge manufacturers don't recommend it. The gold internal wire may very well fail with its use... very hard if not impossible to repair. I would check with your manufacturer
Anyone use a cartridge demagnetizer?
Years ago these devices seemed to be popular with owners of MC cartridges. I owned one when I bought my first MC cartridge (an Adcom cross-coil), and I eventually sold it when I moved back to MM's for a number of years. I eventually returned to MC cartridges, but never bothered with a new demagnetizer. Any MC cartridge users use a demagnetizer these days? Have any MC cartridge manufacturers ever actually recommended a demagnetizer?