try to get a bit of height difference between resevoir and cylinder, the nip[ple being on top of cylinder is a bit of a bollox...let gravity help.. take out too bolts out of cylinder and let it hang down side of box, open bleed nipple and wait till the fluid starts to run out of it, you could tighten nipple up and re fit the cylinder and bleed again as normal or when the cylinder is hanging, clamp the piston some way and bleed it with the pedal and then refit