Alec,
I reinstalled the program and checked the SD Cards for errors (all OK) and made new backups as you suggested.
Merge now works on my backups but I tried merging two of the backup files downloaded from the Technics Web Site (KN3000 A and KN5000A) and these files make it hang.
I downloaded the Technics Site files again, unzipped them, and they now work.
The problem must have been corrupted files.
Thanks Alec,
Walt