If you have any broken ones I would be interested . I want to copy the eq section but need to see one in the flesh as the schematic only includes one mid band.
I have never seen an MCI 500 diagram with only one mid band. Are you looking at the diagram in the technical documents section whoch someone listed as an MCI 500 but is actually a 400 ?
It depends on the particular switch as to how it's configured I believe. They are dual concentric greyhill switches. The bands use torroidal inductors.
I have Nigel Grays console.