I recently purchased Vallejo Model Air metallic Gold (71.066) for some reason I am having difficulty to get the solvent and solute to mix, the paint just appears in chunks of gold color, and a blue solvent. Any good suggestions, I tried placing the bottle in warm tap water, to see if that would help, though it was only done for a few minutes, and seemed to have little to no effect.

Try dropping a stainless steel ball bearing in there and giving it a good shake for 1-2 minutes. I use the AK steel shakers (stainless ball bearings) in my Vallejo paints and they definitely help.

I always put 2 stainless steel bearing ball but i have also made my mixer by changing a economic power toothbrush to stir really good my paits,for me strir is a lot better than shake

what thinner you use?...try with Vallejo AB thinner
http://www.snmstuff.co.uk/product/vallejo-model-air-thinners-200ml/

or i've tried this and i am very happy ...

http://www.scalemodellingnow.com/hntools-ultimate-airbrush-thinner

http://www.snmstuff.co.uk/product/ultimate-modelling-products-airbrush-thinner/