SINGER WRotary (Book 13) - Manual (Page 3)

Wherever a reference is made to turning disc wheel, or
raising or lowering take-up, it is important that the wheel
always be turned away from you as you face the machine.
To Set Needle
Raise the needle-bar to its highest point; loosen the thumb­
screw and press it to the left to permit the shank of the NEEDLE
to pass up between the clamp and needle-bar as far as it will go
—flat side to the RIGHT — the NEEDLE being flattened on
one side so it will set Itself perfectly, then fasten securely by
tightening thumb-screw.
To avoid loosening of the needle, always use a screw-driver,
the needle screw being slotted for that purpose.
The needle, when descending, should pass CENTRAL in
the needle hole from FRONT to REAR, but close to the right
side of the hole.
Use Only This Needle
An illustration showing the exact length of the Flat Shank
Rotary Needle, to use in this machine. To use a longer or shorter
needle will cause trouble and injure the machine.
When ordering needles, attachments or machine parts, do not
fail to give the number of the machine which you will iiiid on the
front flange of the bed plate.