fabricating my own pcb...

[Gordonjcp]

Just two resistors, both about 470 ohms, connected in series across the supply with 100uF caps across them.  This provides an admittedly slightly wobbly 8V supply rail from my 16V power supply.

I really ought to build a proper split supply rail PSU for it all.

What was the Ken Stone one you bought?  If you can give me a couple of clear high-res photos of your board and a link to the instructions and circuit diagram I might be able to help you.