Gottlieb Home Run


I recently got this Gottlieb Home Run pinball machine from a customer that asked if I could repair This is an add-a-ball machine, which means it does not reward free games. This was used to avoid confusion with games that were used for gambling. In essence, a player only plays one game at a time. Most games from this time period can only allow one extra ball per play, in contrast an add-a-ball can add multiple balls per play.

The other unique feature about this game is there is no plunger. Hitting the right flipper will cause the ball to be kicked out between the flippers.

Looking at the game, I realized that it was going to need quite a bit to get it up and running. Furthermore the owner stated the game would not kick-out a ball when it was last plugged in and for this reason has sat for quite a while. I could tell the stepper units and score reels needed to be addressed, too.

Bottom Panel

When working with Gottlieb EMs (Strange World, Sky Jump, Kings and Queens), I usually start with the bottom panel. I will pull the panel out of the game and go through every relay, score motor, stepper units, and reset banks. The power cord will get replaced if needed.

The Hit Unit on this game had taken a beating. The coil bracket was broken, missing screw, plunger and coil stop both were damaged, and there was quite a bit of play on the armature. I went ahead and replaced the broken parts and got this unit working smoothly again. After going through the bottom panel, I moved on to the back box.

Back Box

I started with ball-count unit. This was really gummed up and was taken apart and cleaned. I added two new coil sleeves, re-greased the rivets, and unit was back to moving smoothly. After the ball-count unit, I went ahead and tackled the six score reels.

I took apart each score reel, cleaned the parts, re-greased, and added a new coil sleeve. All six score reels moved smoothly and switches were in the correct position for the 0, 1-8, and 9th position. The last item in the back box was addressing the score relays.

I took apart each relay, cleaned contacts and adjusted if need, and put back together. All relays were now transitioning correctly and this completed the back box. With the bottom panel and back box gone through, I went ahead and plugged in the game for the first time. I left the playfield out of the game for the moment. I want to make sure the game will start before moving on to the playfield. One last step before powering on the game for the first time is to clean the Jones Plug. I use a metal brush and shine up the connectors.

Initial Power

Since this game is an add-a-ball, it’s start up is a little bit different since there is no replay unit. This makes it difficult to set the game to free play. However, someone added a button to the coin door and allowed the game to add credits through this button. This modification is a good idea and noted for other games down the road.

Finally plugged in the game, and hit the “credit button”. The reset sequence began, but would not finish. The score reels reset to zero, and the ball count unit subtracted to zero. However, the ball count unit would not count back up to 5-balls. The score motor continuously ran along with the Add Hit Unit running non-stop. Looking at the schematics I started with the “add ball count unit”.

Add Ball Count Unit Problem

Simple sketch of the Add Ball Count Unit

There are a couple branches off of the Add Ball Count Unit, but the picture above is the branch that I needed to look at. Motor 1A is part of the Add Hit Unit, and I knew it was working correctly because the unit kept running. I checked the DB Armature with my meter and showed that it was closed when DB was tripped. I then inspected DB to make sure it was being activated.

DB Circuit

Since the Zero Position switch on the Ball Count Unit is the easiest to check, I started there. This switch was correct as it was closed on ball zero and open on any other balls. Next problem to check was to the score reels.

I gently pressed down on each Zero Position switch on the score reels and the motor kept running. This ruled out an open switch. However, I double checked the score reels by checking continuity from the far left reel to the far right reel with my multimeter. This also checked out fine. I checked the whole circuit from the coil to the other end, and it showed continuity. After a little bit more digging and searching, I came back to the DB armature.

The problem ended up being the DB armature was intermittent. Adjusted this switch, and game now resets completely.

As a final check, I manually activated the score relays to make sure the score reels were transitioning correctly and the ninth position switch was changing the reel beside it. All of this checked out, and then moved onto installing the playfield into the game.


The playfield was the final part of the game to go through. For the most part, it was in pretty good shape. The vari-targets along with the flippers needed some attention. The vari-targets got cleaned, re-lubed, and adjusted. The flippers received new coils sleeves along with new EOS switches. I then replaced all the bulbs and corrected a few light socket issues. The game is now back up and running correctly!


This was the first time that I played Gottlieb Home Run pinball. The game plays well and has a variety of way to score either runs or points. If you happen to have a chance to play this game, it’s definitely worth a few games.

..and here are the new plastics I mentioned at the start of the post. Unfortunately, I didn’t have a chance to take a photo with them on.

I have a Gottlieb Pro Football that needs repaired in the future and would imagine that it has some similarities to this game.

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