Thanks for that. Mmm, the centre locations look ok but the dimensions look off.
For example, position of oil arm is 160 pixel ( that is distance from left of image to centre = 160pixels ) but centre to rotation point is indicted as 170 pixels which should therefore be off the screen!
I guess you might be quoting the image dimensions before you place them in Facer; I really need the screen dimensions in Facer and/or the scale factors that apply.
In my case, all of my images get halved when I place them in Facer. Is it the same for you? Should I just halve these dimensions? Although, that does not seem right either; the piston arm centre to centre of 208 or 104 seems to be still too big ( ie. three times 104 = 312 so it should be possible to fit three lengths in a watch diameter of 320 pixels but just looking at it seems it would not fit ).