This worked just enough for me to remove the harddrive from a spare-parts machine, but with very little working space.

Todd is right about another step which is not described here, which Nancy already pointed to.

The here omitted first step of keyboard removal, which allows easier cable disconnections, is clearly described in the Dell Service Manual for this type of laptop > https://www.dell.com/support/home/nl/nl/...

There are two shorter screws which connect the harddrive; in this photo they are in the upper corner on the right, but just left from the longer two on the edge. The Dell Service Manual for this type marks them clearly with blue arrows.

Step 9 looked different in my case; the colors were just swapped on the motherboard’s cable-connector and I just had to flip upside a tiny black ‘cable-holder/presser’ from the side of the harddisk. @ Colin Jaffe: the size of the screws holding the harddisk-caddy to motherboard are PH1.5 cross, 2mm thick and only 3mm length. BTW: I had only 2 screws attaching the caddy around the harddisk itself (‘diagonally’ positioned) and they were standard-size; 3mm thick, 4mm long, also PH1.5 screwdriver.