Alan, Gregg, GGG, unfortunately I was at work all day today. But Monday morning I hope to have time to put in the 9V battery and see what that tells us. (A 9V battery I have, a volt ohm meter, not so much, Alan! If it gets down to figuring out which wire is the problem, would a $7 cheapo multimeter from Home Depot do the job? Or what would you recommend, on the definitely economical side? -- But if the next step is that I'm supposed to stick a soldering iron anywhere near the circuitry in my engine, I don't think that'll happen, I'll seek professional help. I'm happy to be able to solder feeder wires to rail joiners, after that I'm beyond my depth!)
Thank you all for your help, I'll hope to report back tomorrow and maybe we'll be a little closer to figuring out the doodlebug at least.