Abstract: In one embodiment, an actuator connected to a printhead structure is activated with a waveform to cause vibration of the structure sufficient to move fluid within a printhead channel adjacent to the structure and not cause the fluid to eject from the channel during a nonprinting period. In another embodiment, a first pulse module applies a pulse at a printhead structure at a combination of voltage, duration, and frequency to cause shaking of printhead structure to move fluid within a printhead channel adjacent to the structure without ejecting the fluid from the channel during a nonprinting period. In another embodiment, an actuator connected to a printhead structure is activated during a nonprinting period to pulse the structure to move fluid within a printhead channel adjacent to the structure without causing the fluid to be expelled from the channel.