IBM 1800409-001A - Manual (Page 296)

4. Remove the old disk by pulling up on each corner while
steadying the board near the disk with one hand (fig. 8.25).
CAUTION: This disk fits tightly, so you have to pull firmly, but
be careful not to flex the controller board while doing so.
Fig. 8.25 Remove the Old Hard Disk
Chapter 8
8 - 4 0 P r i n t e r O p t i o n s