The right-hand cooling block moves rightward and leftward along the two guide rods. During the sample heating, the graphite tube expands, causing the right-hand block to move slightly in opposition to the force of the spring. But if the block does not slide smoothly, excessive force will be applied to the tube. As the result, the graphite tube may be broken or may not be fixed properly.
If the soiled guide rod prevents a smooth sliding, wipe dirt off the guide rods with a clean paper cloth. Perform cleaning once a week when the furnace is used every day, and before measurement when it is used only every few days.