These instructional videos have been released by Bachmann Industries to promote a better understanding of their G Scale product range. The model covered is shown in the banner headline:
I have just come across the three videos above which cover the dismantling, re-painting and reassembly of the ubiquitous Bachmann G Scale Jackson Sharp Passenger Cars by Rail Candy in the USA and thought they might be of wider interest. He runs the Plattsburgh & Poverty Railroad and you can see more of his helpful practical advice on YouTube. I am not sure where you would get the Super Clean Degreaser in the UK but I am sure "other makes are available" that do the job just as well. I think it might be wise to use plastic gloves when using any acidic substance as you never really know what it might consist of.
The excellent series of videos featured below are produced by Garden Trains (a.n.a. Large Scale Online or LSOL for short) and cover a variety of products (mainly Bachmann in origin) which are readily available to the UK market (not least through G Scale Online).