I have the EXACT same problem. My ASR just started doing this. Well...
my work around is using my pc to format floppies for the ASR 10. You'll need a Win 98 Boot Disk & Geibler's EDE program. Here are the links for both.
Windows 98 Boot Disk:
http://www.ensoniqsamplers.org/epsasr/033.html
Gary Giebler's EDE program:
www.soundcentral.com
click on "Musical Keyboard Sound Files" Folder
click on "Ensoniq" Folder
click on "Util" Folder
scroll down to ede107
click on disk under "Listen/Save"
I hope this helps...