I'm not sure if I can help you much, but I still use this receiver and have 5 speakers hooked up and working. I have the 2 front, 2 rear and a center.
I have it on the pro-logic surround setting (there are 4, pro-logic, 3-ch, hall and stadium), then I had to increase the center channel volume (I have volume controls for center and rear channels on the receiver).
Unfortunately, I can't find my manual either, I think it may be around somewhere, so one of these days, I should try and dig it out. I've searched online for one as well, but no luck so far.
Hopefully you can get it working, I'm happy with the surround sound out of my system, not great, but I'm not too picky. One of these days I'll break down and buy a new receiver.