Thanks for the advice Gavin and Nino, that might be the problem - going too heavy with the paint.  

It's being sprayed on not brushed.

The yellow is the one I seem to have most problems with, mainly Im guessing because I put on a white undercoat first (perhaps not lightly enough) because the colour was getting all screwed up and was too thin when I simply tried spraying it straight on top of the black.  As you both say maybe I am ending up with simply too much paint on there, most likely due to a heavy hand and going too fast.

Arrrgggghhh - oh well that was the point of this project.  Get a crappy machine so I can learn the hard way by diving in and messing everything up.  No real harm done since it's not like I'm destroying something of significant value - except for my pride.  lol

Hopefully I will have honed my skills a bit more by the time I'm ready for my next project.