The Drive Busy message indicates that the Zip disc has become fragmented--causing problems in operation. The following troubleshoots this:
- Try reducing the number of tracks being played back or recorded simultaneously.
- Initialize the disc. Note that this will erase all data on the disc:
https://www.roland.com/us/support/knowledge_base/201928459/ - Test with a different Zip disc. Note that the VS-840GX used Iomega 250MB ZIP cartridges as its recording medium. These have not been manufactured for many years in the industry. The best chance of finding one would be online (e.g. Google Shopping).
Notes:
- The data on the zip discs is proprietary and only compatible the VS recorders. If backup ZIP discs weren't created with a connected external SCSI Zip drive, then there's no way of recovering a frozen zip disc unfortunately.
- External SCSI devices have been out of production for many years and are no longer available.