The User manual for CBM 5 1/4″ dual diskette drives are now online. Unfortunately the (a) previous owner had written on some of the pages. I hope you find it useful regardless.
EDIT: As my HDD in my server crashed and I didn’t have a backup of this PDF file, I’ve reconstructed it, while doing so I’ve discovered some doublet pages which are removed in this newer version. If you’ve downloaded this pdf file prior today (29/12-2013) you should get this newer version that fixes some doublet pages.
You can check the version number in the metadata of the PDF file, this new version is called v1.1 under Author (in Acrobat Reader press CTRL-D to view metadata).