My London Decca hums on my Technics SL-110. It get's worse when the arm moves nearer to the spindle. It's not audible when a record gets played but it is not really something you want in your set up.
Just swapped the cartridge to my SL-120 and noticed that there is absolutely no hum. So there are two decks which are quite identical, I'd say they have the same motor unit and the power supply has nearly the same distance to the motor unit, spindle and so on.
I'm really curious where this comes from and of course I want the SL-110 to be as silent as the other deck.