Sorry guys,
First of all - thanks for all your advice. 

What im saying badly here is...

I've got 3 spare System1 processor boards with parts (spider chips etc), plus some already removed spider chips (U3 U4, U5).

I've got a CRO

I've got a  Niwumpf board and the game plays fine with it.

I just wanted to try and resurrect the dead orig System1 CPU board.

I realize it will probably die again, but I've put machine sockets in almost all the spider chip locations so changing is getting easier.

I was just hoping somebody had investigated a bit further along the data & address bus side so I could gleam some advice (Im guessing one of the spider chips is holding down half of the address bus, but I still have U1, U2, U6 hard soldered to the board, so removal will take alot of time, hence the q..

I've already wasted a heap of hours on the System 1 board so I don't really want to give up.

Apologies if it seems like Im stuck on a point here, just trying to clear up where Im at and why im still trying to go down the road less travelled