Klaus, that's a nasty rotor in the picture. Mine looks better than that.

There is joy here. The Volvo has started normally the past couple of morning tries. I think this advice from Klaus was right: "From reading all the new hints, I would guess the alternator is not keeping the battery charged enough to supply the voltage required by the Petronix."

There was corrosion down around the starter solenoid, and when I took the wires off and cleaned everything (and threw away a couple of wires no longer in use) that seemed to do it. Plus I had already done the same cleanup/soldering stuff on wire-ends at the battery and alternator. In addition to your help, the Petronix troubleshooting page and the guy at NAPA also steered me in the same direction...toward the charging/wiring system. Thanks again brickers.

Klaus, I live in Tacoma, Washington. Anything copper here is green.