[still life]

What may be relevant is that they both appear to present not only two drive letters to the o/s but that partitioning utilities regard them as two separate physical drives. The first drive is set as the faked 32gb, the second drive as zero size.

I think the second drive (0 size) is your SD-card slot

Using mydisktest I can get it to create the xbadsect directory and the o/s matches the remaining report (only 1.9 from 32 available, took ages).
Perhaps this is where I am going wrong, if I run the instructions as above (with only the default "bad blocks" option checked) then it just zips through saying all 32gb are fine.

I

double check your memory size with h2testw, it should also report 2GB ok

[I went through exactly as per your instructions the first time and then as my version, no difference]

Either way Chkflsh opens up as expected (it also shows the null drive as a seperate pysical device rather than a simple second partition ), running the slider down below 1.9 gb on the hacked drive and proceeding as instructed has no effect.

Any ideas as how to proceed? I have some feeling that it is linked to the aspect of the "zero" drive but I cannot fathom how to eliminate it.

you should see the hacked 32GB in chkflsh, that's the part to work with anyway
if I remember correctly, I also did things slightly different:

I made the new partition on slot 1, FAT32, slider a bit below the reported size
and didn't mess around with a tiny FAT16 partition

Does anybody have any experience of operating these with micro sd cards?

I'm running a 4GB card without issues, you could try 8GB but as said, not all players support that size