I'm now looking at using phosphor-bronze strip on the locos, but I need to try out my design - tomorrow
Well, we used to say in the RAF "Tomorrow we'll get organized", but tomorrow never came. I did try out the phosphor-bronze strip, but it doesn't like being bent sharply through 90 degrees, and there are lots of bits of snapped-off strip which have vanished into the carpet.
I realized after a while that I could do something like I did on the man-rider, so I broke out the PB wire again and tried out some designs. Again, there are lots of bits lost for ever - springy wire tends to spring off into another dimension if, like me, your finger-tips have the sensitivity of a couple of house-bricks after decades of being pierced with sharp points, hacked with sharp blades, and getting stuck with super glue
Anyway, the two locos have finally been outfitted with self-centering devices:
The Eimco compressed air loco - lots of space underneath for a good length of wire.
The battery loco - lots of room under the rear end, but a bit tight at the front, until I realized I could fix it to the underside of the motor with superglue.
The resultant wires are blackened where they show, and aren't too obvious from normal viewing distance:
The couplings certainly self-centre now, but I haven't had a chance to try them out round my 6" radius curves, as the layout has been split into its 4 parts and distributed around the house until I can get permission to reassemble it on the dining table.