I took the kit back to NZ with me on the plane, ahead of our other stuff that was in a shipping container, hopeful that a few hours spent adding the valve gear would see it running. In Christchurch, I was fortunate to meet up with a very welcoming group of modellers who meet once a month to chat about trains. When I went to shown it to them running, I found I'd mounted the drivers on one axle backwards, causing a dead short. That was embarrassing, let me tell you. However, they encouraged me to carry on and fit the valve gear. I did so, only to have it jam up solid.
I could see that the crossheads jammed against the cylinders. Maybe the crank eccentric on the new drivers was too big? I checked the drawings and saw the new brass drivers were actually too small for a Wa anyway. The driver diameter of 3' was written on the W drawing, but on the web I found Wa loco drivers were slightly bigger. I'd been very lucky to find another Gardner Wa kit a few months prior and decided to pinch the drivers and cylinder castings from that.
After checking the plans further, I spotted that the cylinders and valve bracket were actually mounted 1.5mm too far back, when compared to the drawing. I never noticed it before and dunno why this was so, considering both mounting points are fixed in the kit. That was the reason the crossheads jammed up when the driver cranks rotated all the way forward. It wasn't to do with the drivers. There was only a fraction of a millimetre interference, but that was enough.
To add to the fun, I then found the front crankpin screws hit the inside of the crossheads. The new cylinder centres were about 0.7mm too narrow, or the new wheels too fat, or the crankpin screws too long, or some damn thing.
Either way, I fixed it by thinning down the screws and widening the whole cylinder chest. I'd had a guts-full by this time and just threw a bit of brass and epoxy at it. The cylinders are now a couple of scale inches wider than prototype but I don't care. I'd much rather have a loco that runs.
With a new gearbox, universal joint, torque arm, new motor, completely new suspension, replaced bearings and guides, new springs, cylinders (widened and in the correct location), reworked crosshead guides, new drivers and the reversing bracket in the right spot, it ran ... like a dream. Surely not, I said to myself. But I looked again and it obstinately refused to run like crap. I kept going out to make a cup of tea and sneaking back in, as if to catch it by surprise.
After fourteen years of head-scratching, rebuilds, redesigns, threatening to smash it with a hammer, de-soldering, burned fingers, swearing and frustration, I had the finished chassis of my NZR Wa class loco running like silk on the test track. It was getting juice from two AA batteries but I wasn't fussy. The bloody thing was running.