Hi, Ken:
As DickH reports above, to follow Portland, all you need are the four simulcast control channels (and even more specifically, barring a system malfunction, all you need is 858.73750).
The fill-in (intellipeater) sites do not carry all traffic, so if you're looking for specific talkgroups, that may be why you are not hearing anything.
Try programming a system with just the single control frequency I identified above and see if you get better results. Although I strongly recommend programming this site with a "rebanded" band plan, it is not necessary for this particular system, at least at this time.
joe