Thanks 
I managed to get the top off (eventually - I'm sure you can't be meant to open these things up!) and move the spring over to the SCSI one, though if this one does actually work I will be astonished - it is probably completely dead. I can't test it for a few weeks as I'm not at home where my Macs are until then - that gives me some time to hopefully scavenge some Zip100 discs though, as the only ones I currently have are Zip250. A shame that I didn't come across a SCSI Zip250 drive, but I suppose 100 MB is enough for most vintage Mac files anyway!
Anyway, many thanks for your help
May I just ask...have you worked for Iomega at some stage? Just that you seem to know absolutely everything there is to now about all types of Zip drive!
PS when I come to try it out, should I download the IomegaWare drivers for any of my Macs, or will it plug and play on OS 7.6, 9.1 and/or Tiger? (both the Scsi and USB one will work on the G3, so do both SCSI and USB need/not need drivers for 9 and X?) I was a little concerned that those drivers might add a ton of extensions to my slower Macs, so would prefer to avoid them unless absolutely necessary.
I managed to get the top off (eventually - I'm sure you can't be meant to open these things up!) and move the spring over to the SCSI one, though if this one does actually work I will be astonished - it is probably completely dead. I can't test it for a few weeks as I'm not at home where my Macs are until then - that gives me some time to hopefully scavenge some Zip100 discs though, as the only ones I currently have are Zip250. A shame that I didn't come across a SCSI Zip250 drive, but I suppose 100 MB is enough for most vintage Mac files anyway!Anyway, many thanks for your help
May I just ask...have you worked for Iomega at some stage? Just that you seem to know absolutely everything there is to now about all types of Zip drive!PS when I come to try it out, should I download the IomegaWare drivers for any of my Macs, or will it plug and play on OS 7.6, 9.1 and/or Tiger? (both the Scsi and USB one will work on the G3, so do both SCSI and USB need/not need drivers for 9 and X?) I was a little concerned that those drivers might add a ton of extensions to my slower Macs, so would prefer to avoid them unless absolutely necessary.