Hi Martyj - Martyw here 

It's probably no use shielding the hummy speaker if it's being driven by a hummy signal.

Quite possibly, the hum is coming from the main PSupply board, and you should probably make sure the caps in the main PSupply board are correct.

Depending on the type of buzz (i'd have to hear it) does your machine have a switchmode Psupply in it?
I'm assuming some newer machines do have these?

At worst case, it's simply poor design, and no doubt can be modified to cure the shortcuts the manufacturer made 

I'm in Melb too, happy to assist if required, i seem to always be at markc's these days hahahahaha.


Oh yeh, good luck *NOT* buying something at markc's, everytime i go there i buy something hahahaha.
Supporting the cause .....

Marty.