1.) Did you test the tubes?
2.) Clean all the controls? Including the "level" controls on the back.
have you powered the amp up at all? If not Use a variac or Dim Bulb tester (incandescent light bulb in series with the power cord. Search Dim Bulb tester in the DIY Forums) for the 1st power up, or you risk loosing a capacitor. If everything is fine (no smoke, arcing, fire, etc.) when you get to a 100W bulb, then hook it up to wall power. MAKE SURE speakers or a dummy load is connected to the outputs or you can lose them.
What are the "LEVEL" controls set at. Full clockwise? They are basically a second set of volume pots so that in case of a volume inbalance you can balance the volume at the back of the amp and then control the volume from the main volume control on the front. Put them at FULL CLOCKWISE or anti clockwise (which ever gives you the most volume.)
I get 1.4oHms on the 8 ohm setting on my 400, so what you're reading is the static reading of the secondary for the output transformers. I would think it's ok.
Larry