Thanks you very much for this "hard to find" service manual.
Will help a lot in repairing this receiver.
Text excerpt from page 4 (click to view)
How to Adjust the Rotating Phase of the Gear, Main Cam
1) Push down the hooking catch of the CHAS. MECH, and remove the TRAY. 2) Align the arrow mark of the Gear, Main Cam with the black round mark of the CHAS, MECHA as shown below. 3) Confirm that the Slide, Mech Cam is located in the right position, then insert the TRAY gently. Caution: If the rotating phase of the Gear, Main Cam is incorrectly adjusted, the chucking operation and tray movement will have malfunction.