This picture shows the lumps of Milliput which I have used to build up the gap on the corner of the coal rails on one side and level up the poor fit on the other side. Also some other bits filling the joins above the buffer beam.

I used a mini drill to level the tender sides on the inside, then I filed the filler flat with the body. I used a razor saw to start the gaps between the coal rails followed by a needle to open up the gap. All looks fine now.

Poor picture but shows the cylinders taking shape, should have been 5 parts but ended up as 8 parts. I will fit the slide rods before attaching the cylinder sides. Then try and fathom how the fit the cylinder assembly to the chassis