David,
You should check with the RAG (Roland Users Group) - their home page is at
www.daytonamusic.com/rag/ I seem to remember that both the floppy and the ZIP drive are custom, not the standar PC variety, and, when ordered from Roland, are quite expensive. If the problem you are talking about is with your ZIP drive, you may want to try the new disk - this helped me when my G1000 had a similar problem. However, the easiest way to copy the contents of the ZIP disk to a new media is to use the RDBM (Roland Database Manager) on your PC to import all the styles and MIDI files in, and then to export them to the new media.
Hope this helps.
regards,
Alex