Thanks Simon, I can see why the shading looks a bit off. The basic colour I used was buff, so I thought burnt umber would be a good shade colour, but it was too dark and when I went lighter it's gone orangey. I should have read the tube (it's a Scale75 Artist's tube) which says the buff colour contains synthetic iron yellow oxide and mars black. So probably darkening it with a touch of mars black or even Payne's grey would have been a better idea do you think?
Thanks for the comments on the mechanic, I did feel happier about him (he's the most recent of the two). And I did paint the lettering on the shoulder flash. That scared me as it's a huge badge. But I used Abteilung 502 oil paint and was able to get some letters formed (mostly it's squiggles that look a bit like letters). Glad it looks ok, thanks for that.