(1) The runner is too large to modify the mold;
(2) The runner cooling is not enough to extend the cooling time or reduce the temperature of the tube;
(3) The mold release angle is not enough to modify the mold to increase the angle;
(4) The matching between the concave arc of the runner and the nozzle is not adjusted and matched;
(5) The inner surface of the runner is not only light or has a mold-removing chamfering repair mold;
(6) The outer hole of the sprue is damaged and repaired;
(7) Grab lock without sprue.