Turntable hum problem after demagnetizing

Also, make sure a wire didn't break off inside your interconnects RCA's ends.

Also when I touch the tonearm the hum increases = Ground problem.

There also is static if I clean a record with my carbon fiber brush or touch it to the stylus = You have static build up on your carbon brush. This can eventually happen overtime.

After using it, I now have a huge hum that wasn't there before = possibly indicates a damaged cartridge which is highly unlikely.

Recommendation: Start with a new carbon brush demagnetizer. Disassemble and reassemble all connections, including possibly replacing the ground wire (make sure it didn't get pinched or something). Re-demagnetize with the Benz demagnetizer. If this doesn't work, try relocating your TT to a different AC circuit, along with AMP and speakers....if the hum changes (louder or quieter) you may have a grounding problem not related to your TT. But this is getting to be a longshot and if your house was suddenly having an issue with ground, you would have some other evidence. But I have seen this before so I wouldn't rule it out. If all this is working, borrow a different cartridge and possibly TT if you can and see if that fixes the problem....chasing ground hums beyond a TT and cartride can be very frustrating and usually requires some training and tools.....however, an electrician can determine pretty quickly if you have a ground problem.

Do you have another cartridge you can swap in place of your Benz LP-S to see if the hum goes away? If not, you could buy an inexpensive one and try it. Obviously if the hum goes away the Benz cartridge is damaged, if the hum is still there the problem is somewhere else. Make sure your table and arm are properly grounded.

Was aways for a few days, so just got around to disconnecting the cartridge. Hum still there, but slightly less - only slightly more now when touching tonearm, but very loud if I touch the hookup leads (red, yello, blue, green). I will try rehooking the leads tomorrow - as Paul2240 suggests - I have otherwise disconnected and reconnected the phono cable from both ends. The ground wire on the phono cable looks to be undamaged and all other visible wiring looks undamaged. I don't think the AC is the problem - there are 4 other components hooked up to the circuit - no issues.

Try this - get a piece of wire, strip both ends and connect one end to the grounding post on your phono stage. Then try touching the other end to tonearm, turntable subchassis, turntable spindle and turntable motor. As you go through these check for hum. I have on the odd occasion managed to eliminate hum from earthing various turnable components.