I was a bit worried, as I offered the Phillips-head screwdriver up to the three screws on Percy’s coverplate, that I would find the two axles were driven by a gear train, the connecting rods coming along just for show. That would defeat the exercise, or at least require further testing to ensure Percy could run without the secondary connection between wheels. Fortunately, this was not the case: Percy’s front driver is driven by a vertically-mounted motor inside his huge saddle tank, with the worm between the two drivers, and the connecting rods drive the rear driver.
After taking the model apart, my first task was to draw a 3D model of the parts as built by Bachmann. Using this model, which you can download from OnShape, I’ll be able to design my experiments.
Pembroke:87 
Different set of stories, but still British, “If you can keep your head when all about you
are losing theirs”.
I feel like my Disasters outnumber my Triumphs, though I do try to keep the two imposters equal.