Never leave the plunger in the gooseneck (particularly when newly installed) for more than 1 hour without cycling the injection system, unless the temperature of the melt pot has been turned off, or turned down to the point where the metal solidifies. If by chance, the plunger does seize in the gooseneck, the unit will have to be rebuilt. Give us a call and return the seized unit. We can have a new or re-built plunger and gooseneck assembly to you within about 24 hours.