Hi, did you try with the same Unit settings on both modules? You could try copying your old DrumIt.dkit kit bank and kit to the new module and switch to it to see if it makes a difference. Another way would be to use my program DKit Manager to import your Unit settings to the new kit bank of the 5mk2.
It very much could be the SD card. Did you have the external SD card reader modification installed on the original DrumIt 5 and if so did you try the old SD card in the new DrumIt 5mk2?
If you didn't have the mod installed and you don't mind opening your original DrumIt 5 (it's quite safe there's a guide
here) you could take its SD card and try it in your new 5mk2.