VERTICAL STRIPES
This defect may be caused by defective needles.
It is easy to find out this defective needle because the butt of this needle is usually lower than the others.
Defective needles:
1.Bend needle will contact with the wall of the needle housing strongly.
2.Needle with warp is contacting the retaining needle bar strongly.
3.Bending of the top edge of the needle bed forming an obstacle to the needle.

WHEN MACHINE STOPS AND HAND CRANK DOES NOT TURN
If the width of the work zone of needles does not correspond to carriage(small or large) during the ascending and descending of the needles, the carriage will turn back without going to the end of the needle work zone. This will cause needle jam. In this case, level the release lever and turn the hand-crank gently to move the carriage right to left and vice versa.
Some of the needles may accidentally jump out of the needle track resulting in the carriage hitting the needle butt. In this case, press the raised needles downwards and the carriage will move.