[Rusty Heap]

possibly a bad or poor line neutral.

You have a digital volt meter like a Fluke?

Do a voltage check between your Line Neutral coming from the power pole, and your earth ground bus bar.

You say your LIGHTS FLICKER, on this one phase of your box. That may be the key. It's either the hot, or neutral feeding that half the circuits. I'd compare the steady state voltage between the 2 line voltages coming in, as well as the reference to ground. Something is up with that one phase.

If the PUD has checked it, I'm sure they've blessed their side of the power meter and that's their responsibility, the house side of the power meter is yours. If you're not comfortable, a quick house call of an electrician is obviously way over due if your lights are flickering.

remember all voltage is referenced to something, whether 12VDC in a car, or in your house. you may have a fine voltage feeding all circuits, but if your return line neutral is marginal, that's key.