The return of the white expanded polystyrene background, if only because there was so much junk on the layout that it was quicker to put a sheet of polystyrene over the top than tidy up.
Today I've double-motored a Hornby Class 90 and equipped it with a Lenz LE1025A decoder. The benefits of fitting a second drive unit to the cruder Hornby (and Lima) models include better haulage and more reliable starting. This loco now pics up current from all wheels and is driven on all axles, even if it is only by third-rate pancake motors. I also take the opportunity to remove the wheels fitted with traction tyres and replace them with the metal equivalents from the left-over trailing bogie. This gives far better current collection, and any loss of traction can be compensated for by adding extra weight.
Sometimes double-motored locos don't seem to give their best when partnered with feedback decoders, but I tend to get away with it more often than not. This example is certainly a success - quite a smooth runner by Hornby standards.