ThomH has a point, I did get my Microdrive to work, but only when a full moon fell on a Tuesday, and only then it would give me about 10 minutes of use starting at 7:17pm...
I've still got it somewhere, along with an Opus Discovery disc drive that allowed the ZX Spectrum to use 3.5" floppy discs as if they were Microdrive cartridges if memory serves me right (sometimes it doesn't, I think I'm getting old).