@ Gottlieb.
"Middle early" (I assume those squirrel maker marked EICKHORNs are earlier) EICKHORNs don�t have any screw, they do have the "built in" or integrated scabbard mouth (as I think it is shown here and my dagger also has this configuration). Only later ones do have the H�RSTER configuration with one screw on the reverse.
Keep in mind that also fakes do have this H�RSTER configuration but up to now I never have seen or heard about a faked integrated scabbard mouth.
The etching is shown here in pics 6 and 7.
Regards,

wotan, gd.c-b#105

"Never look for sqare eggs" as a late owner of an original FHH-dagger used to say.