I always use heat-shrink tubing now on all switches, if there's even the slightest chance of the soldered areas coming into contact. As you say, moving the wires around can cause this to happen.

You can get packs of heat-shrink from places like Maplins or (sometimes) B&Q or Halfords, I think, but the best place is generally from the tool suppliers who attend model railway exhibitions as they tend to have it in the right diameters for the sort of wiring we do. I'm always running out of packs so buy more than you think you'll need...

Welcome to the wonderful world of railway modelling.  It took me a long time to understand the mysteries of electrics and it very much sounds like you've mastered this quite quickly.  Well done, you just need to tweak your skills now and the advice above is spot on.  I used to use insulation tape until I found heat-shrink tubing - now no more frustrating hours on my back trying to wrap tape around wires in tight places!!  The other thing to remember is to write down your wiring plan (if you haven't done so already), because you can bet your life that mysterious shorts will occur with complicated track plans.  The plan can save hours messing about with a circuit tester trying to find the problem.

Regards

Mike

Nice tidy soldering! use a wire stripper and only take off about 6mm of insulation, tin the wire ends and conections first. Use a fine tip soldering Iron. It goes quick once you get the hang of it.

Hope this helps.