Make sure the ball is sitting close to the fork that throws the ball. You will have to take off the apron to see this. You may also be able to adjust the switch leaf to push the ball closer to the fork.

I had the opposite problem where the ball was hitting the apron and falling back into the hole - my fix was a shield to keep it from jumping out.

The fork is likely worn, and not available from PBR. There are several other fixes out there, look for ball eject threads. Good luck - I know this is frustrating.

Need to assess what the failure mechanism is, if possible.

Sometimes, the outhole solenoid can be firing too weakly because of dirty switches in the circuit, resulting in a weak pulse. In that case, would want to check/clean the switches in the outhole kicker circuit as shown in the schematic.

In other cases, the ball might not be sitting in the outhole optimally as Bill mentioned, and is not being struck properly by the kicker arm.

In some cases, the ball may be going airborne and hitting the underside of the apron. Such may require adjustment to either the ball position or the kicker arm, or both.

I suggest cleaning all the switches in the circuit to the kicker solenoid first and see if that fixes it.

Here is a post with pics of a simple mod I came up with in the 1970s to fix our games on location. This is for the case where the ball doesn't eject because it isn't landing properly in the cradle of the outhole kicker. It's a very common problem with those oval GTB outholes.

https://pinside.com/pinball/forum/topic/gottlieb-72-kicker-not-kicking-enough#post-6075058

- TimMe

Check for a broken jumper wire between the two wipers (the double-wiper set) on the ball count unit. Also check to confirm that those wipers and their corresponding rivets are clean, lined up properly, and making good solid contact. If that double wiper isn't making a good electrical connection with the rivets for any reason, you will get the behavior you are describing.

- TimMe

The yellow highlight on the attached schematic snippet shows the end-of-game circuit. This is the circuit that takes the machine into game over when the last ball has drained.

ball_count_circuit (resized).jpg

Let's take a 3-ball game as an example. What is supposed to happen is that the highlighted rivets on the ball count unit are supposed to be bridged by the double wiper when the ball count unit moves to ball-in-play 3. The ball count unit should advance from ball 2 to ball 3 as the ball is delivered to the shooter, when the ball rolls over the switch at the extreme right end of the return trough. This should occur after the O relay has kicked out the ball, so the O relay should not be energized when the ball count unit advances from ball 2 to ball 3.

When the ball drains after the 3rd ball is played, the O relay pulls in and that causes the score motor to run. The bridged wipers on the ball count unit and the O relay switch will provide pulses to the add ball count unit coil via the motor 1A switch in the end-of-game circuit. Because there are rivets at positions 3, 4, and 5 of the ball count unit, the end-of-game circuit will remain active as the ball count unit quickly steps forward 3 times, one step for each time that the 1A switch pulses. At this point the ball count unit will be in the 6th position, pushing the 6th position switch open. That will shut off the end-of-game circuit, and will also put the machine into game over.

When the machine is in 5-ball play, essentially the same thing happens. However, note that the rivets on the ball count unit for the positions at ball 3 and ball 4 are no longer in the circuit. So, the game will go all the way to the 5th ball before the end-of-game circuit is activated by the final set of rivets. When the ball drains after the 5th ball, there will only be one 1A pulse coming from the end-of-game circuit, which will immediately put the ball count unit into the 6th position for game over.

So what you are describing sounds like something is bridging the end-of-ball circuit one ball too early. Since the ball count wiper that lights up the ball-in-play lamps and the double wipers for the end-of-game circuit are on the same arm of the ball count unit, there shouldn't be any way to have ball-in-play "2" lit and also have any of the double wipers bridged. However, you should check to see if there is some issue with the positioning of the ball count unit wiper arm.

If the ball count unit wiper arm is in the proper position, then it implies that something other than the highlighted circuit is advancing the ball count unit too early - perhaps as soon as the ball drains. That would advance the ball count unit into the last ball position too soon, allowing the end-of-game circuit to be activated one ball too early.

- TimMe

The O relay should NEVER be energized while the ball is rolling over the trough switch. Likewise, the trough switch should NEVER be closed while the O relay is energized. If you have either of those issues, you definitely have an unusual problem. Neither of those scenarios is likely to be happening to your game, but I guess it wouldn't hurt to confirm that.

- TimMe

Oh, one other thing - it's a rare issue, but I should mention it. Since you added the switch blade mod to deal with the oval outhole, that may have created a rogue circuit between the trough switch and the outhole switch that can advance the ball count unit. This rogue circuit gets completed by the ball touching both the mod blade and the outhole switch blade when it falls into the outhole, and it occurs when the wireform of the trough switch happens to be touching the metal runway.

You can test for this issue by temporarily removing the mod blade to see if your ball count problem goes away. If that is what is causing the problem, you can either leave the mod off, or eliminate the rogue circuit by swapping the two wires on the solder lugs of the trough switch, if you want to keep the mod in place.

- TimMe

Good catch. Regardless of what is causing your ball count issue, you definitely want the mod to be shorter so it doesn't touch the outhole switch blade.