Hi, Motorola console question

Thank you for your time in advance... I have a Motorola console SK78 with a stereophonic hi-fi turntable... The tone arm is not attached. At the rear of the tone arm, where the 1 1/4" screw is supposed to go over the mechanism i noticed two impressions on either side of the mechanism that move the tone arm and I assume something is supposed to fit on to the back of said mechanism to keep the tone arm spring from snapping it off. If you are familiar with the model and/or have some documentation that illustrates the parts of model. i would be extremely grateful.

Very Best,

Novice antique radio enthusiast