Thanks guys for the advice.

I was hoping somebody has used a CRO and gone a bit further/ might have some more detailed problem solving advice for the system1 board.

I've used the Pinrepair guide but he stops at checking the data & address bus by saying if you have no data/address signals, game over. I was hoping to go a little more in depth and try and fix. It appears as though potentially one of the spiders is holding the data or address bus down, but im flying blind as I have no info to go on.

I realise Im wasting a heap of time, but I'd rather keep the orig board going.