I think "Cleanliness is next to Godliness" when it comes to spray guns .

I'm quite fastidious with my cleaning. I've paid the price 2 times when taking shortcuts and won't do it again.
I have got a pretty good system down now that allows me to do a very thorough job, and only use about 300ml of thinners.
Disposal of too much old thinner is difficult in a suburban back yard, so I try and minimise as much as possible.

I believe I have the same Star .8mm gun as you Jon. What thinning ratio are you using?

For acrylic lacquer, I do a 50/50 mix and run my nozzle pressure at about 18 PSI. My fluid flow is typically 1/2 a turn in (decreased) and air flow control open full. Unfortunately it's not always a one-size-fits-all thing with the settings, but that's where I start.