Pressing start runs the reset sequence, then the Game Over relay trips again before a ball is served, and further presses of start do nothing.

Game Over relay trips again right after start: dirty Lock relay switch

Cause: A dirty switch on the Lock relay. On the schematic the same trip path also runs through the zero switches on the player unit and ball count unit and through the Coin relay, so those are the other suspects.

Checks

• Trace the Game Over trip circuit on the schematic.
• Check the Lock relay switch, the player unit and ball count unit zero switches (a ball count zero switch stuck closed causes the same fault), and the Coin relay switches.

Fix

• Clean and adjust the Lock relay switch contacts.

Unplug the game before working on relay contacts: EM wiring carries line voltage in places.

Systems

• Electro-mechanical

Games

• Freedom (EM)

Related tips

• Game starts but flippers are dead and nothing scores: dirty relay switches
• Ball count runs to 10 and the game resets endlessly: dirty ball count stepper
• Start button does nothing but the start relay works by hand: dirty inertia switch
• Next ball sometimes not served after a drain: C relay path switches, then new rubbers
• Start sequence keeps cycling after storage: clean the switch contacts and plungers
• Game resets but the outhole relay never fires: feed wire hanging by a strand
• Ball count stays at 1 after each drain: dirty secondary trough switch
• Game keeps cycling the reset and starts in Game Over: dirty P5A switch and shorted wires

Source: Pinball Repair help group!! (Facebook group)