Getting one of the crosshead pieces the wrong way around, and the slightly misshapen cylinder bracket where only the tip of the iceberg when it came to the problems I've had trying to finish the assembly of the moving parts in this kit. I've lost track of the number of times I've fully assembled and then fully stripped down and cleaned up the parts for both cylinder assemblies, but it definitely requires two digits to write down. This isn't to say there were any specific problems with the kit, more that as the first locomotive I've assembled there were probably a few things I simply overlooked or didn't think through fully. One thing I did learn though was a simple way of attaching the cylinders to the frames.
I'd already followed Paul's suggestion and filed down the ends of the mounting screws to give a thin point onto which the bolt could be slid with ease, but with the small amounts of clearance, and podgy fingers it was still difficult to get the bolt onto the screw. I tried placing the bolt with tweezers, but the slightest change in pressure and the bolt would be pinging off in a random direction; hopefully somewhere inside the frames so I could find it without spending an hour searching the carpet. In the end the solution was simple; blutack. Simply use a long piece of blutack to gently touch the bolt and then deposit it onto the pointed screw. Simple but it works every time!
I'm not sure I have many tips for anyone else who assembles this kit, other than to take it slowly, do one step at a time and check for smooth running at every stage. The one suggestion I would make concerns glueing the cylinder connecting rod to the crosshead. The instructions suggest doing this before attaching the cylinder to the locomotive by "clamp[ing] the assembly vertically, apply a small amount of [gel super]glue to the pin head only and allow the cross head to fall onto the pin head. Set aside for at least 1 Hr before handling". This sounds like sensible advise but I found that it could lead to the pin and crosshead not being perfectly aligned which would impact on the smooth movement. In the end I left glueing the pin until the cylinder was attached to the frames and the crossheads were running smoothly. At that point I applied a small blob of gel superglue to the pin and then slid it to meet the crosshead. After a few seconds, to allow the glue to start to grab, I then ran the locomotive for about 20 seconds to ensure that the pin and crosshead were perfectly aligned for smooth running and then left the glue to dry fully.
Anyway, enough words, here is what all this has been leading up to, the wonderful little locomotive shuttling backwards and forwards (a bit too fast but I do like to see the motion at speed) with all it's motion in place and moving.