Sky Jump came into the shop via another customer. The description of the game was it worked for a bit, until the owner fiddled around with it and no longer worked. The game sat in a dry garage for over five years. Since I just worked on Strange World and High Hand, I originally thought that it was going to be an easy fix. However, I realized that probably was not going to be the case once I saw it in person 😁. I started the repair by first taking out the playfield and motherboard. I gave the machine a good vacuum and cleaned up any of the debris


I took out the motherboard and started going through every relay and switch. I noticed after a short bit of time that someone did not like to solder. They would just wrap the wire around connections and found this in other spots, too. Some switches were out of the armature and needed adjusted.

The score motor also needed some adjusting. A set of switches could not make transitions due to a bent fork.  Straightening the fork, cleaning, and adjusting the switches now allowed them to transition. I checked the fuses at this point and found two were not the correct amperage. I just threw in two circuit breakers knowing that I will put in the correct fuses when done with the game.


Moving onto the backbox, the credit unit and ball count unit were both sticking. I took apart both units, cleaned, and re-lubed them. Both units were now moving correctly when I manually engaged the coil. Next, I moved to the relays and thought this would take a couple of minutes, but ended up taking a very long time. The scoring relays had rusted over. The screws from the switch stack and the coils ended up breaking. I fought this for quite a while, and finally removed all of them. I replaced most of them with new screws. If anyone is wondering the switch stack screws are #3-48.

Rusty relays
Rusty relays

The last step in the backbox was going through the score reels. All four of the reels were cleaned and adjusted. I did notice that two EOS contacts were missing. I replaced those with new switches.

Powering on the Game

After putting everything back together, I decided to power on the game. I didn’t worry about the playfield (yet). I turned on the game and the two coin door lights lit up. That was it. I tried to manually move the score motor, and it didn’t move. Looking at the schematic, the bounce switch is right after the power to the lights. I inspected this switch and noticed that it was wide open when it should have been closed. This provides power to a majority of the game.

open switch
Switch WIDE open and should be closed.

This now brought power and the score motor rotated. I tried to start a game and the Start relay and Hold relay would engage for a second then release. Both of these need to be on for the game to restart. The cause of the problem ended up being a wiring hack on the coin door. Redoing the wiring created the two relays work correctly. The fuse holders created intermittent power issues. At this point, I switched them out with new ones. After a few more adjustments (Hold relay) the game would now restart and start playing!

fuse holder
One new fuse holder in place in contrast with the old ones.


With the game now playing, I took the time to look at the playfield. I like doing this because the game will tell you want needs to be adjusted. The first thing I noticed was the ball kicker was continuously firing. Upon closer inspection, I could tell there was something wrong with it. Someone (who doesn’t’ like to solder) wrapped some wires around a few of the connections. I cleaned up this problem and adjusted one of the switches and the problem stopped.

I redid this hack. There was no solder on the connections.

The sounds chimes did not produce any sounds when hit. I had the same problem with my El Dorado. The next problem to tackle was the drop targets. They worked okay, but needed a good cleaning and one target had broken. Owner said I could use an extra cactus target that I had on hand and ended up using that.

I ended up cleaning and adjusting the sequence bank as some of the switches were not registering. The flippers felt good on this game and did not need rebuilt. The flippers ended up getting new coil sleeves and a good clean.


This ended up being a bigger project than I initial thought, but was fun to get this game back up and running. The owner is excited to play this game again after it sat for so many years. Sky Jump is a game that I had my collection at one point in time and was nice to see it again in my shop.

2 thoughts on “Gottlieb Sky Jump EM Pinball Repair

  1. Amazing work, thanks so much.

    I am the owner of the machine Troxel fixed, er raised from the dead. I gave it to him in a pretty crappy state. It had been dead in the garage for 5 years and had things living in it apparently. I feel pretty bad about that, but he cleaned it up and got it working so well.

    All the work he had to do with how horribly “fixed” it was just amazed me. That is dedication and it is currently working completely and just needs some love and care physically which I have enjoyed doing.

    Thereon is such a decent person. We go back a decade where he was super helpful with me back then. After I got Sky Jump back, I had an issue (not his fault) and he spent a good amount of time with me on the phone to get it figured out. Taught me how to read schematics over the phone. It was super appreciated and shows his dedication to his work and with his offerings for classes to the pinball community we are lucky to have a local resource like him.

    Thanks for your work on my pin.

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