③Caused by the thread
・Is the timing of the frame closing time wrong?
In the case of the mechanical type, the timing may be out of order if the gear is engaged due to deterioration over time.
In the case of the electric type, the moving motor or amplifier may break down and the timing may be out of order.
・Is the tension of the twisting thread appropriate?
Basically, the tension should be managed by the spring, so if it gets clogged with dust, the tension may drop.
Or the spring may be damaged. (Although it is often a human error)
・Is there a pill on the thread?
There may be pills on the thread.
・Is there any distortion or rattling in the twisting mechanism?
Due to the wear of the constituent parts, the timing may be incorrect or the opening amount may be incorrect.