My first question is : What sort of disks are you using? If you're using HD (PC 1.44 M byte) ones then you will have problems. The density-select hole will mean the disk-inserted sensor is not activated so the drive won't think it's got a disk in it. And even if you cover that hole up, the coercivity of the media is different between DD (which is what you shoudl eb using) and HD disks. The latter will _not_ be reliable! I am in two minds about this recomendation. On the one hand, if you've got no experience of dismantling electronic devices, it may be safer to use a cleaning disk. But those disks are very rough on the heads, I NEVER use one! The 9121 comes apart quite easily. After disconnecting the cables at the back, it's a few screws on the back and the cover comes off (lift the back edge first I think). Each drive is hald down by 3 or 4 screws, and there are 2 cables to uplug. Then one screw on the back of the drive chassis itself holds the cover on. With that removed you can lift the presure pad carefully (this is a single-head drive) and clean the head with a cotton bud dipped in propan-2-ol. But then I've worked on many, many such drives... -tony