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It could be a mechanical issue even though you've cleaned it some. The torsion spring around the gear shaft is the only thing that gets the Bonus step unit to step down. If there is any extra friction in the unit it's not hard to overwhelm the torque the torsion spring provides. Another possibility is that the unit was disassembled at some point (perhaps to be cleaned) and the torsion spring was not returned with the appropriate number of turns - typically about 4 turns.

To test the friction theory you can manually advance and reset the Bonus Unit. To do so properly push the advance or reset solenoid plunger all the way in and just let it go and let the springs do all the work. The hardest test for the torsion spring is to return the Bonus unit to the zero or reset position from the 1st position. If you can't do that reliably by manually resetting it you probably have a mechanical issue to sort out.

/Mark

In case it's not a mechanical issue - could you post a photo of the score motor sequence chart and tell us what some of the relays involved are named: specifically 5B, 6B and K relays. I don't have that schematic.

Many Gottlieb games have a motor chart stapled to the inside of the cabinet near the motor

I'll take a stab at it without the score motor sequence chart. Here's a redraw of the bonus countdown circuit. Remember on '70s Gottliebs, there is a circuit that adds 1000 to your score for each bonus, and another circuit (this one) that decrements the bonus unit one position for each pulse it gets. The way Gottlieb gets bonus multipliers of 2X or 3X is by reducing the number of pulses that get to the subtract bonus unit coil - that way, those thousands getting to the score reels just keep on adding up because it takes the bonus unit longer to decrement all the way to zero, at which point the zero pos. bonus unit switch will open, stopping the bonus count.

In this redraw, the score motor produces 6 pulses that get to the subtract bonus unit - 5 from the Motor 4A switch and one that comes in last from the Motor 4D switch.

In the event that you only have achieved 1X bonus: Once the bonus starts, the K switch closes, the zero pos. bonus unit switch is closed (because you have accumulated some bonus), and the 5B switch is closed because you haven't achieved 2X bonus. So all 6 score motor pulses can get through to the subtract bonus unit coil. Each pulse getting through moves the bonus unit 1 step closer to zero at the same rate the 1000's score reel is getting pulsed - a 1 to 1 bonus.

In the event that you have achieved 2X bonus: the 5B NC switch opens, which means the pulses from Motor 4A can only get through Motor switches 2D and 3B. That's 2 pulses - a 3rd pulse gets through from Motor 4D. So while the 1000's reel gets 6 pulses, the subtract bonus unit coil only gets 3 pulses....which effectively doubles your bonus score before the subtract bonus unit reaches zero.

The 3X bonus switches the 6B M/B switch so you only wind up getting 2 pulses through to the subtract bonus unit coil while the score reel gets 6 pulses....effectively tripling your bonus score.

It sounds like you're having trouble getting the subtract bonus unit coil to fire reliably during the bonus countdown, and to a lesser extent, during reset. The AX switch in this circuit comes into play during game reset, which may affect your reset issue. If the game is resetting correctly most of the time, the Motor 4A switch is probably OK, though I'd check/clean it and make sure it's opening/closing consistently all the time. Check that AX switch carefully - those AX relays are notoriously finicky.

For the bonus countdown problem, I'd look carefully at the switches involved in getting those 6 pulses to the subtract bonus unit coil:
- the zero pos. "bonus" unit switch (that one is probably working correctly, otherwise, your reset wouldn't work - but check/clean it)
- the N/O K switch - make sure that one is closing reliably
- the N/C 5B switch - make sure it's staying closed until you reach double bonus.
- possibly the M/B 6B switch, though if that one weren't closing, you'd still get a pulse from Motor 4D...but check it anyway.

Use the wire colors on your original schematic to identify the correct switches.

Close Encounters (resized).jpg

This is all assuming that you don't have a mechanical problem with the bonus unit decrementing.

My money's on the K switch because if 5B wasn't closing, you'd still get 2 pulses through Motor 3B and 2D, and one through Motor 4D...you'd effectively have double bonus all the time. If 6B weren't closed, you'd still get one pulse through Motor 4D - your bonus unit would decrement once every score motor cycle.

Good - you're making progress! Switches can look clean and look like they're touching, but still not be making electrical contact.

If you're getting 6X bonus, I'd check that 6B make/break switch carefully. If 6B wasn't closing , you would be getting 6K points going to score reel for every 1 pulse (through the Motor 4D switch only) that gets to the subtract bonus unit coil....that would be a 6X bonus.

Remember: This circuit we're talking about only decrements the bonus unit - it doesn't score the bonus points. Points are actually scored somewhere else where 6 pulses per score motor cycle get to the L relay. So if that AX switch in this circuit were malfunctioning (by being closed), you would be getting fewer bonus points, not more, because the bonus unit would decrement to zero faster.

Good luck - you'll get it!

I'm just curious if your schematic has a score motor sequence chart on it. They're usually down toward the bottom left corner of the schematic - a small chart that has degrees of score motor rotation along the top axis, and switches along the left axis. The chart is just a bunch of black dashes....anything like that on your schematic?

you're right about the gantt chart looking thing for the sequence/timing diagram. Some of the late gtb EM schems don't have it.

the ABC stuff is just the types of switches: A=normally open, B=normally closed, C=make-break

if the letter has the circle above it, the switch uses large contacts.

does your bonus unit step down very rapidly ("machine gun firing")? If not, is the K relay powering and staying powered the entire time the bonus is counting down ... no release/repowering?

if K is not staying powered, can you post a pic of the zero switches on the bonus unit when reset, step 1 and step 2? iir, there's a make-break switch that must be adjusted correctly and the typical problem is when the reset solenoid plunger slams into the coil stop, the vibration opens the switch and the K relay loses power. You get erratic bonus countdown instead of a steady rapid cadence.

if K is releasing you shouldn't have the score reels doing anything when the bonus unit isn't decrementing if all the switches on K are adjusted ok.

because stuff is happening rapidly, it can be helpful just before triggering the bonus countdown to disconnect the score motor ... most games of that era had a "service plug" that let you disconnect. Then you can rotate the cams by hand and watch what is happening.

don't do the manual rotation when one of the 120V solenoids is going to fire ... if you rotate too slowly, the fuse will likely blow on those.

That schematic is unusual. That AABCCC sort of notation was usually written as 2A, 1B, 3C in alphabetical order (not like Motor C2 with BBAAA). And I don't recall seeing the circle or asterisk notation around the switches. If the circles are large (or high current) contacts, what are the asterisks? The lock in switch maybe? I wonder if this schematic was drawn by a new, or contract draftsman.

I think the only place I've seen the circle notation is motor switch charts in the parts manuals.

if I had to guess (apparently I do), maybe the * denotes a hold-in switch. I don't recall that being documented anywhere tho.

the /xxx notation on the wire colors is also odd. Maybe it's an engineering / prototype schematic or if that's what was sent with the production games, they didn't bother to redraw it due to the low production amount.

I found this table in the Parts Catalog last night. The table also gives great info regarding the formed blades and their association with the motor switch positions, including how they change the Motor 1D to alternate timing for some machines (a different formed blade).

I hadn't noticed that table before. This is from the 1974 catalog:
Gottlieb 1974 catalog motor switches (resized).jpg
Similar tables appear as far back as the 1966 catalog. The part number represents an entire switch stack that can only be used in specific score motor positions probably because of the different shapes of the formed follower switches that the cams or pins activate.

can you post more pics of the schem ... especially the score reel area and whatever relay powers that score reel. The circuit controlling the score reel may be mostly independent of the circuit controlling the bonus unit, so the problem could be elsewhere than discussed already.

yes, the K relay should power and stay powered for the duration of the bonus countdown.

it sounds like you're losing step-down pulses for the bonus unit ... e.g. only one pulse path is getting thru ... or some of the multiplying is done elsewhere and that's not working right.

another test is jumper closed the zero switch on the bonus unit that has one blade connected to the step-down coil. If your bonus unit steps down a lot faster, then that switch needs adjusting to get really good overtravel. You don't want it popping open when the plunger hits the coil stop.

can you take a video of the bonus unit during bonus countdown?