An injection molding apparatus, comprising: a manifold defining a resin channel for conveying liquid resin from an injection molding machine toward a mold cavity; a nozzle for conveying liquid resin from the resin channel to the mold cavity; a valve pin configured for linear movement along a longitudinal axis of the nozzle to control flow of liquid resin through the nozzle; and an electric actuator having a body containing an electric motor and a linear drive shaft ( 1 0 2) with a bore, wherein both the electric motor and the linear drive shaft are contained within the body of the electric actuator, and wherein the valve pin ( 3 6) is directly or indirectly coupled to the drive shaft within the bore, such that linear movement of the drive shaft produces co-linear movement of the valve pin, wherein the electric actuator body has a top opening and the bore extends through the length of the drive shaft ( 1 0 2) to allow manual adjustment of the valve pin position; the bore extending through the drive shaft is internally threaded and the valve pin is directly or indirectly coupled to the drive shaft via an externally threaded valve pin nut threadingly engaging the internally threaded bore; the valve pin nut has a tool-head engagement structure for manual positioning of the valve pin and valve pin nut with respect to the drive shaft, characterized in further comprising an externally threaded lock nut threadingly engaging the internally threaded bore and disposed adjacent a side of the valve pin nut opposite the valve pin. a manifold defining a resin channel for conveying liquid resin from an injection molding machine toward a mold cavity; a nozzle for conveying liquid resin from the resin channel to the mold cavity; a valve pin configured for linear movement along a longitudinal axis of the nozzle to control flow of liquid resin through the nozzle; and an electric actuator having a body containing an electric motor and a linear drive shaft ( 1 0 2) with a bore, wherein both the electric motor and the linear drive shaft are contained within the body of the electric actuator, and wherein the valve pin ( 3 6) is directly or indirectly coupled to the drive shaft within the bore, such that linear movement of the drive shaft produces co-linear movement of the valve pin, wherein the electric actuator body has a top opening and the bore extends through the length of the drive shaft ( 1 0 2) to allow manual adjustment of the valve pin position; the bore extending through the drive shaft is internally threaded and the valve pin is directly or indirectly coupled to the drive shaft via an externally threaded valve pin nut threadingly engaging the internally threaded bore; the valve pin nut has a tool-head engagement structure for manual positioning of the valve pin and valve pin nut with respect to the drive shaft, characterized in further comprising an externally threaded lock nut threadingly engaging the internally threaded bore and disposed adjacent a side of the valve pin nut opposite the valve pin. an electric actuator having a body containing an electric motor and a linear drive shaft ( 1 0 2) with a bore, wherein both the electric motor and the linear drive shaft are contained within the body of the electric actuator, and wherein the valve pin ( 3 6) is directly or indirectly coupled to the drive shaft within the bore, such that linear movement of the drive shaft produces co-linear movement of the valve pin, wherein the electric actuator body has a top opening and the bore extends through the length of the drive shaft ( 1 0 2) to allow manual adjustment of the valve pin position; the bore extending through the drive shaft is internally threaded and the valve pin is directly or indirectly coupled to the drive shaft via an externally threaded valve pin nut threadingly engaging the internally threaded bore; the valve pin nut has a tool-head engagement structure for manual positioning of the valve pin and valve pin nut with respect to the drive shaft, characterized in further comprising an externally threaded lock nut threadingly engaging the internally threaded bore and disposed adjacent a side of the valve pin nut opposite the valve pin.