A system for calibrating needle lift in a spray gun assembly, the spray gun assembly including a nozzle having a nozzle seat and a stepping solenoid actuator for moving a needle to a closed first position when the needle engages the nozzle seat, the system includes an actuator control system having: a user input device; a processor; and a memory for recording a virtual needle position of said needle; characterised in that the actuator control system includes: an actuator sensor structured to detect changes in the current characteristics over time in at least one actuator line conductor and to provide an output signal, wherein the at least one actuator line conductor is the conductor that supplies power to said at least one stepping solenoid actuator; wherein the actuator control system is structured to: detect an identifiable anomaly in the current output signal caused when the needle engages the nozzle seat; disengage the at least one stepping solenoid actuator when said identifiable anomaly is detected to arrest the forward motion of the needle; and update the recorded virtual needle position of the needle so as to indicate that the needle's current position is the closed first position such that the actual position of the needle is recalibrated with the virtual position of the needle. a user input device; a processor; and a memory for recording a virtual needle position of said needle; characterised in that the actuator control system includes: an actuator sensor structured to detect changes in the current characteristics over time in at least one actuator line conductor and to provide an output signal, wherein the at least one actuator line conductor is the conductor that supplies power to said at least one stepping solenoid actuator; wherein the actuator control system is structured to: detect an identifiable anomaly in the current output signal caused when the needle engages the nozzle seat; disengage the at least one stepping solenoid actuator when said identifiable anomaly is detected to arrest the forward motion of the needle; and update the recorded virtual needle position of the needle so as to indicate that the needle's current position is the closed first position such that the actual position of the needle is recalibrated with the virtual position of the needle. an actuator sensor structured to detect changes in the current characteristics over time in at least one actuator line conductor and to provide an output signal, wherein the at least one actuator line conductor is the conductor that supplies power to said at least one stepping solenoid actuator; wherein the actuator control system is structured to: detect an identifiable anomaly in the current output signal caused when the needle engages the nozzle seat; disengage the at least one stepping solenoid actuator when said identifiable anomaly is detected to arrest the forward motion of the needle; and update the recorded virtual needle position of the needle so as to indicate that the needle's current position is the closed first position such that the actual position of the needle is recalibrated with the virtual position of the needle. detect an identifiable anomaly in the current output signal caused when the needle engages the nozzle seat; disengage the at least one stepping solenoid actuator when said identifiable anomaly is detected to arrest the forward motion of the needle; and update the recorded virtual needle position of the needle so as to indicate that the needle's current position is the closed first position such that the actual position of the needle is recalibrated with the virtual position of the needle.