Since the weekend I visited Rainford when I messed up the pickups on the Hudson-Hunslet there hasn't been much time for doing any modelling. Today though I set myself the challenge of fixing the pickups once and for all.
My hunch was that the 0.112mm phosphor bronze wire I had was perfect as it was springy enough while having a tiny surface area so as not to introduce lots of extra friction. What I realised this morning was that as the wire came as a coil it naturally curves in one direction and so is springier when fitted one way as compared with the other. Last time I think I had it curving away from the wheels as that was the most natural direction given where the pickups are mounted. This time I've fitted it so that it is always wanting to curl towards the wheel instead. Fingers crossed this seems to work really well as even though it moves about a bit as the wheels turn it naturally springs back and continues to press on the treads. With such a light but continuous contact I've found that the slow running has also improved considerably.
So having finally solved that problem I think I'm now happy with all the current prototype parts; the chassis is easy to put together, the etches fit the body print and nicely reproduce the makers name on the front, and it moves as it can collect power! So the next step will be packaging things up as a kit and working out how much interest their is so I can figure out the size of the first batch.