How to fix/remove hum problem from 1970s Dual turntable

[Guest]

Mint condition 1970's Dual 1228 t-table has hum problem which I can't find to fix. I have other Dual t-tables as well, so I know where to find the usual hum causing culprits. Everything else works perfect, it's frustrating. Any comments I'd be glad to hear.

 

[Guest]

I've only dealt with one Dual and that was to remove all the metal pressings hanging underneath which had gone wrong. I'm more into the manual minimalist Thorens approach.

Here are general rules for hum busting as I know them:

1) Check the amplifier is earthed at the power socket but ensure the turntable is not.
2) Check that there is an earth wire from the turntable to the amplifier.
3) Is there a slight crackle when you touch the headshell -- check that all cartridge terminals are securely wired and that the arm body is earthed to the amplifier.