Done that mate in the past (Removed nut and piston etc and cleaned with petrol) it's no good. Although I guess I could try using carb cleaner, I never would use WD40 as this will leave a greasy residue which would gum it up.

The new one is VAE06 which is supposed to be a replacement for VAE01, I will try and get a pic of the new one, the little nut at right at the end of the thread and has a spring directly beneath it where as the old one has the nut and the little disc directly beneath it.

Martin