If it is an Amiga external 5.25 inch drive, then it should be set to 80 tracks for 720K floppies, 40 for 360K floppies.
High Density (1.2MB floppies) generally age the worst, they have the thinnest magnetic layers. So even if the drive inside the case has been replaced and is compatible, chances are the floppy would be blank.
Remember, to read the data you would have to setup PC0 or PC1 mountlist file in Devs, to use the right file system (CrossDOS) when reading from or writing to the drive.
Or plug one into a CBM Bridgeboard, which is another way of connecting them to an Amiga, but not on an A1200.
