Hi Bill_EM +
"sometimes faults" are problematic. I try to find out about "is there a pattern in the fault - reproducable ?".
In pinside we once had an discussion "what is a turn of the Score-Motor (?)" - since then I always write about "a Gottlieb-Score-Motor does a turn of 120 degrees (means a third of a revolution)" - these motors are built 120 degrees symmetrical. On position 1A on the motor there are switches that are closed five times when the motor makes an turn of 120 degrees --- closed 15 times in a full revolution - so 15 different edges on the bottom cam (level A) close an specific switch. If these edges on the bottom cam are just a little different one to the other(s): The switch may close or "just not close".

Raise the playfield - make "300 points plus an bonus" - watch the motor - do You see a turn of 120 degrees (?) - make it again and again "300 points plus an bonus" --- see it (?) - every time a turn of 120 degrees. Toggle-off the pin - with some paint or a marker or a piece of tape: Mark one of the three Home-Positions (motor is at rest at an Home-Position). Toggle-on the pin, start a game - make the maximum of bonus --- then do none or once or twice "300 points plus an bonus" so the motor stops on the marked "Home-Position" --- THEN trigger the Outhole-Switch so the Bonus-Count-Down starts. How many thousends points do You get -
then on the next ball again --- make the maximum of bonus --- then do none or once or twice "300 points plus an bonus" so the motor stops on the marked "Home-Position" --- THEN trigger the Outhole-Switch so the Bonus-Count-Down starts. How many thousends points do You get -
then on the next ball again --- make the maximum of bonus --- then do none or once or twice "300 points plus an bonus" so the motor stops on the marked "Home-Position" --- THEN trigger the Outhole-Switch so the Bonus-Count-Down starts. How many thousends points do You get -
Do this several times - do You ALWAYS get the same amount of "thousands of bonus" ? IF (if, if) "Yes": Would be a strong sign / hint that the problem is on the motor-1A-Switch. Greetings Rolf

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Hi Bill_EM
Your (post-16) "usually scores no more than 2000" is not precise --- I am trying to find out about a pattern. The "500, 300, 3000" is another problem - maybe related --- I would like to stick to "Bonus-count-Down problem". It is getting late in Switzerland - I go to sleep, till tomorrow. Greetings Rolf

Hi Bill_EM
You may read the text following --- the important text comes after ++++++++++:
thanks for doing the test(s). What I meant is: You start a One-Player-Game. You play Ball-1 --- before loosing the ball You bring the Bonus-Unit to maximum (question: Is 10*** or 15*** or 20*** the maximum ?) --- You look at the Score-Motor - one of the home-positions You have marked --- by chance the motor is in the marked home-position --- if "not" You then do the make "300 points plus an bonus" once - You maybe do it twice --- You do have "max bonus" and You do have "motor is in marked Home-Position" - THEN You let drain the ball and count the many 1000 points You get. The pin gives You the second ball - You do the same procedure ... You get ball-3, ball-4 (same procedure).

I take the first line of Your results "4000 4000 3000 4000 3000 4000 3000 4000" --- AAA:
You did expect "10*** or 15*** or 20***" but You only got a total of "4" then
You did expect "10*** or 15*** or 20***" but You only got a total of "4" then
You did expect "10*** or 15*** or 20***" but You only got a total of "3" then
You did expect "10*** or 15*** or 20***" but You only got a total of "4" then
You did expect "10*** or 15*** or 20***" but You only got a total of "3" then
You did expect "10*** or 15*** or 20***" but You only got a total of "4" then
You did expect "10*** or 15*** or 20***" but You only got a total of "3" then
You did expect "10*** or 15*** or 20***" but You only got a total of "4".
Hmm, another interpretation of the result is BBB: "4 out of 5 pulses in a turn of 120 degrees (motor), 4 out of 5 pulses, 3 out of 5 pulses, 4 out of 5 pulses, 3 out of 5 pulses, 4 out of 5 pulses, 3 out of 5 pulses, 4 out of 5 pulses".
It is hard to write so the other person understands --- we are on a tecnical problem - I must ask: Do You mean "AAA" or do You mean "BBB" ?

How does the feature work "collecting bonus at end of a ball" (?) We may think "The Bonus-Unit / Bonus-Ladder is stepped down one step and so we get 1000 points added to the Score-Drum".
To be precise: In the pin there are two separate features happening at the same time --- not related. One feature is "toc, toc, toc, toc, toc" five pulses per turn (120 degrees) of the motor - five times "step down the bonus-unit / bonus-ladder". The other feature is "toc, toc, toc, toc, toc" five pulses per turn (120 degrees) of the motor - five times "add 1000 points to the Score-Drum". As both features start at the same time and the features both end at the same time: We may think "The Bonus-Unit / Bonus-Ladder is stepped down one step and so we get 1000 points added to the Score-Drum" - but two features are happening - at the same period of time.

I believe the feature "stepping down the bonus-unit / bonus-ladder" works fine in Your pin - the motor runs and rhythmically "toc, toc, toc, toc, toc - little pause - toc, toc, toc, toc, toc - little pause - toc, toc, toc, toc, toc" the bonus is stepped down --- see the JPG, lower part in post-15. See my "rosa / pink" marked "motor-1A" --- rhythmically five pulses on a turn of 120 degrees (motor).

See upper part of the JPG - another switch on motor-1A-position fires rhythmically pulses (also 5 pulses in a turn of 120 degrees (motor))

++++++++++: It is complicated - the fault can be on many places --- lets do little steps in testing. Here https://pinside.com/pinball/forum/topic/reading-gottlieb-schematics#post-2634425 SteveFury shows his 24Volt Test-Light. Make You such an Test-Light. On both ends / wires You may have an gator-clip to clip-on at a solder-lug somewhere in the pin. Some places are hard to get at - (almost) impossible to clip-on. HowardR came-up lately with an excellent idea (and it works) --- a safety-pin on one end - we can insert (almost parallel to the wire running - insert the tip of the safety-pin into the wire - through the fabric-insulation - tip and metal-wire get into contact.
Whatever way You do it - do set permanent "my yellow-1 or my yellow-2" scenario. IF (if, if) "switch-motor-1A" is good: The Test-Light MUST flash-up FIVE times when the motor makes a turn of 120 degrees. Question: In Your pin ? Depending on Your answer we will proceed. Greetings Rolf

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Hi Bill_EM
my mother tongue is german - (words from a dix) - slangy / sloppy / casually written text in english: I maybe do not understand. "Hot" to me means: Using a meter and the meter says "Hot - current may be ready to flow - maybe means 'connection' " --- what is Your "hot" ?
You say "put the lead ..." - does this means You use an Jumper-Wire instead of an test-light ? You did put the lead FROM WHERE ? to 1A inside switch --- Your list in post-9 says "Motor-1A is in S-position - Inside switch is for to reset Tens and Hundreds Score-Units - second switch is for to add the player-unit - THIRD switch is for scoring and adds bonus". So 1A INSIDE SWITCH is the wrong switch --- it must be THIRD Switch with wires bl-or, red+wh.
You say "put the lead ... triggered ... light went on five times and scored 5000" - do You mean "lights went on five times and the Score-Drums scored five times 1000 points" ?

Look at the JPG in post-23 - not mentioned in the JPG: On the left side of the coil on L-Relay are soldered-on two wires of color-black --- THIS is the clip-on point for (test yellow-1) Test-Light. The other clip-on point for (test yellow-1) Test-Light is solderlug with wire-bl-or at motor-1A-THIRD-Switch. Maybe hard to get at - hard to clip-on a gator-clip there - may want to use the "safety-pin trick" (?).

"Test yellow-2" is almost the same as test-yellow-1 --- from coil on L-Relay side two wires of color-black --- to "Switch on J-Relay, Solderlug with wire-bl-or".

Establish permanent "Test-Light-yellow-1" or "Test-Light-yellow-2" --- plug-in the main power cord, toggle-on, start a game, play --- the pin must act "as before" --- and new - every time the motor turns a turn of 120 degrees: Your Test-Light flashes-up five times (((no other strange behaviour of the pin - no strange adding 5 times 1000 points))).

Please clarify "text in post-25" - please do set permanent "Test-Light as yellow-1 or as yellow-2" - write about "reliable / always / exactly flashing-up five times of the Test-Light when the motor makes a turn of 120 degrees" (?) Greetings Rolf

Hi Bill_EM
thanks for clarification. You did on Your own a good, helpful test - Test-Light clipped-on at "side-wire-black on coil on L-Relay" - and the other end on the INSIDE-Switch on motor-1A --- the schematics at schematics-I-17 says "wire-of-color-blk+wh, wire-of-color-red-wh" - I assume You used lug "blk+wh" (?) --- and the pleasing result was: The Test-Lite flashes-up (rhythmically) five times in a turn of 120 degrees (Score-Motor). EXACTLY THIS result You should get when clipping-on at THIRD switch on motor-position-1A - clip-on at lug-wire-of-color-bl-or.
IF (if, if) the Test-Light lights-up and stays lit: THIS THIRD-Switch on motor-position-1A is FAULTY. Greetings Rolf

Hi Bill_EM
a kind of add-on to my post-30: In the beginning I was chasing a theory - by now my theory has been proven wrong --- so I write: My (proven wrong) theory was: 1 or 2 or 3 ... of the edges on the motor at position-1, level-A, actuating the switch with wire-of-color-bl-or, wire-of-color-red+wh - edges slightly different / other --- NOT truely closing motor-1A-switch. So I said - lets try to find a pattern --- YOU always max the bonus - YOU always bring the motor into "marked" Home-Position - then let the pin collect the bonus - YOU make an statistic and we can clue from the result of the statistic. Obsolete - obsolete --- NOW we are on the problem / question: How, why is this motor-1A-switch faulty always closed (?). Greetings Rolf

Hi Bill_EM
my Surf Champ has only a few wires on the Score-Motor having nylon insulation. Do not hurry with these many wires on Your Score-Motor. See the JPG in post-15 - the switch in question (motor-1A) ALSO helps on another feature --- lets question this other feature: Here http://www.ipdb.org/showpic.pl?id=388&picno=18207&zoom=1 the Eject-Holes on the left and the right - when an Eject-Hole is lighted: You must get Zero or 1 or 2 or 3 BONUS - depending on how many Drop-Targets You have made to drop.
Question: Does this feature (Eject-Holes and some bonus) truely work in Your pin --- the motor-1A switch is used for this feature. Greetings Rolf

Hi Bill
I made a fault in thinking - I thought "Eject-Hole feature tells us if the motor-1A-THIRD-Switch is faulty" --- this thinking is faulty - the Motor-3C, -3B, -1D do the pulsing on the bonus - motor-1A-THIRD-Switch being good OR being faulty always closed.
To the "Eject-Hole feature" You report 'fault in counting points' - I would like to look at later.

I want to stick to motor-1A-THIRD-Switch - I believe "stuck - faulty always closed". You once tested (for fun) motor-1A-INSIDE-Switch - using the Test-Light and in this test the Test-Light flashed-up FIVE times. Please use the Test-Light (again) on motor-1A-THIRD-Switch - test again - do You get FIVE times flashing or do You get "steady lit". I assume You clip-on correct so when You have "steady lit": The motor-1A-THIRD-Switch MUST be faulty always closed --- please inspect this motor-1A-THIRD-Switch. Greetings Rolf

Hi Bill
thanks for the observation. I go to sleep - too late for me to start brooding --- first idea: some kind of "backlash" (?). You may have to unsolder wires --- I can see wirings in the schematics --- I cannot see "shorts" in the pin.
the time I had to bring back to life my bought pins: I did some rude things --- to unsolder is a wire: That is quite easy to be done - BUT soldering-on back / again at this place down in the bottom cabinet - at the sidewall - angled - hmm. So I sometimes was rude - I bought me from K-Mart (such stores), automotive department, car electrics: Male and female plugs I can crimp-on with a pair of pliers --- instead of unsoldering a wire: I took an old scissors and cut the wire (about 3 to 5 inches away from the solder-on lug). A cigarette-lighter to burn away the fabric insulation - then cramp-on the male and female plugs (can all be done with one hand). I then could plug together or un-plug - as I needed at a given time.
So You want to contemplate (?) about "how good am I (means You) in unsoldering / soldering back on at these 'hard to get at places in the pin' " - (((and may buy such K-Mart plugs)). Till tomorrow. Greetings Rolf
P.S.: I just read Your post-37 --- have a very good look at this third motor-1A-switch "drop of solder ? doghair crap of wire ? maybe YOU make the short with these clumsy gator-clips ?

Hi Bill
me getting up this morning - reading good news --- great, YOU found the problem. In the pin some stuff (switches) are mounted side by side - making an short. In the schematics these switches are shown on places far apart --- very hard to get the idea of "creating a short".

Thanks for the picture in post-39. Silly me - I happen to like to see "topics marked as solved" - please in here - (beeing in post-1) - on top, on the right --- some icons to click-on - please click-on "Mark as resolved". Greetings Rolf