You have to puzzle it a bit together but the basic variables for everything are Surface, Illumination and Assembly. Especially considering that 3310 and 3988 are based on A9800, altough this is valid for every optical System.
What kind of problems? If its high LOD i wouldnt call that actually a problem. It would be interesting to compare it with your results, Alextwokay´s problem sounds like something is wrong with the illumination so yours should score signifacintly higher while showing the same pattern.