The Husqvarna Viking 150e is a slightly updated model of the original Viking 150. The new machine was released in 1989 and sold until 1992. The Viking 150e has an electric foot pedal that is more accurate than the mechanical pedal that powers the earlier Viking 150. It's not complicated to open a Viking 150e, but find a service manual for it before you tinker with its operational parts.
Remove the screws that hold the machine to the bottom plate with the screwdriver.
Unscrew the screws on the top of the machine and remove them.
Remove the screws from the sides of the machine.
Pry the machine open gently with your fingers. Pry the nameplate off of the front of the sewing machine with a flat head screwdriver. You now have total access to the Viking 150e's motor.