Hi Classicpinballs
a good site: http://www.zaccaria-pinball.com/ - then click on "Electromechanical Games" and You land here http://www.zaccaria-pinball.com/em/index.html - then click on the schematics of Aerobatics.

I do not see an "Score-Reset-Relay" in the schematics --- I see an "Reset Up Relay" - (in a functioning pin) this does not constantly run - it might be rhythmically actuate as the Reset-Relay is constantly pulling and the Score-Motor constantly turns and turns and turns - in Your friends pin ?

In the schematics I see "Switch on Reset-Relay when closed makes the motor run and run and run" - the switch has soldered-on "wire-yellow" and "wire-green-red" - is this the switch You mention in post-1 ?

The Coil on the Reset-Relay has soldered-on on one side: (Most likely TWO) wire(s) of color-black - on the other side of the coil is a short wire running to "Switch mounted on the relay - the so-called Self-Hold-Switch***" - lets try and CHEAT a bit - have the Score-Drums resetted - toggle-off the pin - sneak-in a stripe of paper in-between the contact-points on the switchblades of this Self-Hold-Switch*** - make it electrically open. Then toggle-on and start a game - what happens ?

Self-Hold-Switch***: As You are at this switch: Look-out for "IS THIS SWITCH TRUELY OPEN when the relay is not pulling" ?

"Sneaking in a stripe of paper" is not fixing - it is only a test in troubleshooting. Greetings Rolf

Hi Classicpinballs
I am not very happy with the schematics - some places the wire-color is not mentioned - a switch is drawn but no text to it - the Score-Motor-Switch-IND-C is a three-bladed M&B-Switch and it is drawn five times in the schematics - the text at the drawing of "Score-Motor" I do not understand "Brake-Part is '24 Volt broken off' " - hmm, never read such a text.
The schematics uses "Reset Relay and Reset Up Relay" - but Your picture in post-5 clearly shows "Reset Score Relay and ...ore Relay" --- the drawing of switches on Score-Motor-INDex-Cam lists switches A,B,C,D means four switches and in the picture in post-5 we see five switches - You write about "two tiny wires not connected to anything" - hmm, what wires ?

I have taken Your picture and added twice the letters "A" through "K" - questions: are truely "left A connected to right A" ? B to B ? ... K to K ? The tiny wires - are "E and F" ???

Lets find out about the switches on the INDex-Cam --- I believe "my K and my J" is IND-D is the Self-Hold-Switch for the Score-Motor run --- try - when the pin is idling - motor not running: Gently press the "my K blade" down a bit to get into contact with "my J blade" and then let go --- the motor should start running and do a turn of half of a revolution --- DOES the motor do this ? If Your answer is "Yes": We can identify "my K and my J" beeing Switch SCM-IND-D (?).

The schematics says "SCM-IND-A is an Normally-Closed Switch for Game-Relay, SCM-IND-B is an Normally-Closed Switch for Hole-Up-Relay" --- "my A and my B --- also my C and my D" are Normally-Closed-Switches - lets assume "all good".

My working thesis is "my E and my F" are the switch with UNUSED wires (is this true ?) - lets assume "all good".

So the remaining three blades probably are "the problematic zone" - "my G, my H, my I" --- when the motor is not running means at rest: "My G and my H" must have contact --- as the motor starts turning and when it is turning: "my H MUST move away from my G --- my H must move towards and get into contact to my I" --- question: DOES "my H moves AWAY from my G - "my H LOOSES contact with my G" ???
"my H has in Your picture soldered-on Wire-Yellow" --- the color of "my G" is well, something-with-maybe-blue ? --- please look at the steady pulling Reset-Relay - at the switches - at the switch "a short wire runs from one side of the coil on Reset-Relay to blade on the switch" - THIS Switch: Do You see the same wire-color something-with-maybe-blue on THIS Switch ???

Please have the pin toggled-off and the main power cord unplugged (Safety Reasons) - have the Score-Drums manually resetted - sneak-in a stripe of paper in-between "my G and my H" - to securely keep the contact-points of the two blades separated / apart --- then plug-in, toggle-on, start a game - what happens ? Have the symptoms of the fault dissapeared - means the motor does NOT run - Score-Reset-Relay does not actuate ?
Greetings Rolf

0Aerobatics-SCM-IND-pinside-Work-02 (resized).jpg