If so could you please do me a huge favour and post a picture of the wiring.
I have just had miine installed by a good friend and they seem to work well but there is a strong buzzing noise if the bare silver wires arent touching the outer wood in the cavity.

I would love to see a picture of the wiring cavity of some fully working ones to compare?

Please help
Sounds like you need to improve your ground. The shielded cavity should have a screw or a lug of some type that one of the grounds is soldered to. You need to create or fix that connection.

Check the ground connections and re-flow them if you're not sure. This sounds like an execution more than a wiring issue, unless that ground was omitted completely.