Fault 1: jump needle and bolt Cause analysis: sewing machine spindle, spindle bed, under the bobbin case and the bobbin in the sewing machine, they are layer upon layer be buckled. Place bobbin is the most prone to failure, it has a pointed to the front, in the long run, this tip will go bald, will jump needle and bolt. Solution: change the shuttle. 

Fault 2: up and down the line is not symmetrical Cause analysis: the role of the bobbin case are adjusted up and down the line, if the line is not symmetrical, up and down that screws in the bobbin case. Solution: screw tightly or loosely screw. 

Fault 3: needle don't hang line Cause analysis: the handle on the machine needle is flat, below the eye of a needle, good quality machine beard needle handle and needle is vertical, poor quality will not vertical. The first thing to choose good quality machine needle. Needle on backwards or does not reach the designated position, also will not hang line. Solution: correct installation method is to make the machine machine needle needle slot on towards the left. When installed needle, should end. 

Turn fault 4: don't move, or the more heavier Cause analysis: oil the sewing machine has a special sewing machine, sewing machine oil normally is transparent, put long will become yellow, but can be used. Many people in the oil is not sewing machine oil, but in cooking oil, transformer oil, etc., the oil viscosity, after a long time, could let the machine did not move. Someone is sewing machine oil, but they put oil on the beverage bottle, because the bottle walls have sugar, also can cause oil viscosity, turns a sewing machine. Solution: open parts clean with oil. 

Fault 5: pedal sewing machine, but don't go line Cause analysis: sewing machine cow leather belt is loose. Solution: it needs to be a tight tight or a change. And maintain the method of the belt is on some oil regularly, don't let it out.