I just compared the sourcecode that is called when dumping for 1.24 and 1.54. While I didn't do that in 1.24, in 1.54 I dump the firmware from the drive's bootcode. Need to check why I changed this. While the result should still be the same, it could be that right after entering the bootcode, the drive sometimes returns the wrong data.
I'll try to find a way to work around this - hopefully during the weekend.