I've found that a huge chunk of archiving floppy disks is just the process of coaxing bits off of a disk.
I always start with a preservation stream dump, and if the kryoflux software fails to decode a sector, sometimes feeding it to a third party program (such as HxC or the tools with the PCE emulator) may decode sectors the that Kryoflux won't.
After that, it is a matter of performing additional inspection, cleanings, and re-dumping of the disk surface until I am sure it won't do any better.