Jeff:
1) Manually pull the lever that is normally triggered by the solenoid. The arms should be parallel when the tone arm drops. If not that tone arm and the sensor arm are not properly aligned.
There are instructions in the service manual that show how to adjust this.
The arms will (in most cases) always be parallel at rest position. There is a "V" groove cut into the mechanism that lowers and raises the arm and this will always force it to center.
What you need to determine is if it will stay parallel without any external force.
2) The optical switch (plate with slot cut in it) that regulates the lateral movement of the tone arm needs to be precisely adjusted. If not the arm will not be parallel during play.
Derek