2005 Zoom MRS-1608 Digital "Multitrak" Studio Recorder Repair

Very nearly gave up on this one - a combination of red herrings throughout, and almost missing software. I've put this up to share info with anyone else in a similar situation and decided to archive the software I was able to get, to preserve it. People still like using these machines, and they're of an age where the drives will start to fail!
Resources:
Zoom MRS-1608 User's Manual
zoomcorp.com/m...
MRS-1608 Recovery CD ISO (open directly for the files or burn your own disc)
archive.org/de...
GUIFormat - format 32GB or larger drives to FAT32
ridgecrop.co.uk...
KVR Audio forum post, covering a different model but with relevant info
www.kvraudio.c...