Use the map(x, in_min, in_max, out_min, out_max) function:
myServo.writeMicroseconds(map(originalPWM, 0, 255, 1000, 2000));
Use the map(x, in_min, in_max, out_min, out_max) function:
myServo.writeMicroseconds(map(originalPWM, 0, 255, 1000, 2000));