I'm not totally following you and I do not own the game or the schematic.

But, bear in mind that the (GTB) schematic is drawn to show the state where the game has fully reset, ball is in shooter lane and game is unplugged. Normally that lack of power means relays are no longer "pulled in" and the drawn state of the switches reflects that. But you show a latching relay which can remain "pulled in" even after power is removed, due to the adjacent relay coil's armature latching it in the pulled-in state. So the schematic for these latching relays may appear backwards at first glance.

Can you elaborate?

Here are the relevant bits of the schematic:
King Pin A relay (resized).jpg
The relay table shows that the A/Reset Completed relay is an interlock relay with 6 switches (5A, 1B). Five are normally open (5A) and one is normally closed (1B). As jeffc mentioned the state of the switches on the schematic can be confusing since the relay holds its position when the game is unplugged, but as long as you have 5 switches of one type and 1 of the other and they're actuating appropriately your relay is probably fine.

The A relay is one of several that can make the Score Motor run so it seems more likely that the A relay is releasing prematurely rather than the Score Motor is stopping too soon. Once activated by the S/Start relay and the motor 2C switch, the A relay should remain tripped until the A Reset relay fires when all the score reels reach zero and the motor 2B switch closes (at the very end of the Score Motor cycle).

If your score reels aren't resetting all the way I'd suspect that one or more of the score reel zero position switches aren't opening appropriately.

/Mark

Those switches should only come into play at the very end of the reset sequence when the game is ready to serve up the ball and add to the ball count. I think the game should be able to complete the rest of the reset sequence with those switches open.

But I'm still not clear, what specifically isn't working?

What is your A-reset relay doing? Anything strange mechanically (slipping?)

As MarkG says, S pulls in which starts the motor. During this motor cycle, motor switch 2C will pulse to actuate 4 things: play meter, subtract replay unit, reset ball count unit and the A relay.

I'm assuming you can observe the A relay activate.

Now that A has pulled in, it should not let the motor stop until A-reset fires to unlatch A. And it could take a few motor cycles because some reels will have to increment from 1 all the way around to 0. A-reset can only fire when all four score reels' reset switches are closed.

If you set your reels to 1111, what do they show when the motor stops early? The same showing each time?

Could *ALL 4* score reels' reset switches be closing too early (adjusted wrong)?

There is no lock-in circuit that could prematurely open to lose your A relay (which is powering the motor) so if you are getting different scores after each reset attempt from 1111, I'd suspect the closed switch on A that powers the motor might be dirty or lacking enough bias to keep it closed.

Note: I'm working off of a 74 1p Sky Jump schematic.

I suppose that if the motor is stopping prematurely due to poor NC switch on A relay, then the A-reset would never fire and A relay would remain latched.

Also, if your score reels are only getting to 4's or 5's it could be that the A relay is not powering the motor at all and you are only seeing the last few 1A motor pulses to the score reels while the S relay finishes up its time with the motor.

There's a switch on the Ball Count Unit that cuts power to most of the playing and scoring parts of the game:
King Pin Ball Count Zero Position switch (resized).jpg
It's common on many Gottlieb games. What happens is that after resetting the score reels and all the game features, the ball in the out hole fires the O/Ball Return relay which in turn kicks the ball through the trough to the shooter lane. On the way, the ball closes the Trough switch which steps the Ball Count unit out of the Zero position which closes the switch above and provides power to most of the rest of the game.

When debugging with the playfield up you can usually let the game reset, then tap on the Trough switch from underneath the playfield to advance the Ball Count unit and power the game.