SunStar HC Series User Manual page 31

② When inserting the needle, make sure that the
groove of the needle is facing front. Shaft of the
needle should be inserted completely into the
needle bar.
[CAUTION 1]
For special threads such as artificial silk, turn the
needle slightly to the right to prevent thread breaks
(see [Fig.4-19]).
[CAUTION 2]
If the needle is not inserted all the way to the top of the needle bar hole, timing of the machine will go
off, causing broken needles and thread breaks.
Needle insert hole
Front groove of
the needle
groove
[Fig.4-18]
[Fig.4-19]