As I have stated before, and I will mention again, I work with and for Ketron on various projects as an Engineer and one heavily involved with the GUI, design and code of our products, so from a design prospective this is information I ought to know ... so yes, this is an official procedure (which you may verify by contacting us at firstname.lastname@example.org if you wish to get more info on).
I have not made this available because this is the first time I am seeing a customer of ours complain of a 'Checksum' error! It's best to provide detailed 'engineering' information only when needed - else you may end up with a lot of people 'experimenting' with thier products and then getting back to us for solutions to problems that could have been initially avoided all together. I believe however, that we have provided our distributors with this information to use when/if needed.
Mind you, this procedure mentioned above is NOT for 'Init Phase error' correction (which is related to the Hard Drive or Sound board) but for the Checksum error the customer above was requesting assistance with.
I don't know why 'his' flash went bizar but there are a couple of environmental factors that could make a flash memory 'forget' it's contents and he could have encountered one of such ... I don't know for a fact and won't speculate either.
The file - 'Audb0000.pcm' is infact for KetA02.
Hope this answers your questions/concerns, and let me know if I can help you with any others.