The eject arm has officially been replaced, and the old worn-down arm has been discarded.

If the original issue persists (the ball not moving into the chute), further analysis will be performed.

At the very least, the eject arm has now been replaced. This would be considered a consumable/wear item.

Check Electrical compoments - Result: Working Properly

Closer inspection reveals that the eject cam arm has worn down. The “sharp right angle” is gone. This wear may be causing improper contact when trying to eject the ball, which may explain the erratic behavior.

Solution: Replacing the cam arm will ensure proper contact and eliminate this condition as a variable.

Next Step: Purchase a replacement Cam Arm.
Part Name: Eject cam arm - #A-8247

Unfortunately the current source I located is sold out.
https://www.marcospecialties.com/pinball-parts/A-8247