I had very mixed results doing mine. The sprocket cover and indicators worked really well. Belt covers were pretty good.
However the side panels and beer tray were dreadful - I got this weird silver blooming all over them, especially on the beer tray.
Here's my best and worst piece side by side after dyeing, for comparison.
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The beer tray was pretty black beforehand - perhaps a teeny bit faded, but nothing like this.
My concourse plans are well and truly stuffed now.