Thanks for the reply Roman. Below is a copy of a ticket I have just sent regarding my test prints.

Printer is now operational and I have been attempting the test print. First print was not good enough to measure in Z as the first few layers were deposited in the waste powder bin having been wiped out by the blade. It was good enough to measure in X and Y and these were way out, measuring just 34mm x 35mm. I unbolted the top and adjusted the galvo drivers by quite a lot and did a re-print. This time the print went fine with no layers lost. However, the X and Y were still a long way off at 36mm and 38mm - too much for the computed scaling. I have now altered the galvo drivers again and the test pattern is now overlapping the print chamber. Is this okay? Another test print planned for tomorrow. The quality of the print is disappointing with the bottom surface being convex and the top surface being very concave. Again, I cannot check the Z scaling because the surfaces are not flat. What is causing this? The surface seems very molten as the laser fills in the surface. Should I speed up the laser, widen the hatching or raise the surface temperature?

Maybe other could chime in with their thoughts too.