Hi there, can anyone tell me if it is easy to change the hard drive unit in a Sony RDR HX900 ? I have a chance to buy one that has had the 160gb Unit removed (why i dont know) and the guy has tried to put a 20gb drive in to test it and it comes up with HDD Error (or drive error)... Wondered if anyone knows if this is likely to indicate a bigger issue? If I were to check the unit out, is there any kind of formatting process i could use to get the unit up and running to test it?