Well thanks to you guys i finally got the machine wired up correctly and fired up without issue (other than no sound).
A big thanks to all who helped educate an idiot, in particular Studley and ddstoys.

Does anyone know where i can get replacement sb-300 ribbon cables?

Thanks all.

Always nice to report back what the problem turned out to be

Sound cables here:
http://www.ebay.com/itm/Orignal-Stern-Pinball-Sound-Cable-SB-100-300-DUAL-GOLD-PIN-/300796678133?pt=LH_DefaultDomain_0&hash=item4608e10ff5

Keep in mind that if the existing cable tests OK (each wire is continuous), it is not likely to be the problem.

cheers
Ian