A few days ago I brought my first machine home. A Gottlieb Gladiators system 3. Everthing worked 100% fine and looked good before purchasing. Last night while playing, immediately after the shaker engaged, the left flippers (both upper and lower) stopped working... leading me to believe there is probably a loose connection somewhere. Taking a closer look, I can’t seem to find any loose connections, and everything looks visually ok underneath. Checked the fuses (F20 & F21) and they tested out fine. Have not checked the coils yet but that’ll be my next step. The right flippers (both upper and lower) and everything else on the playfield works completely fine.

Ran the diagnostic test, and still somewhat confused on how these read out....

As this is my first machine ever, not sure what else to do next.... so please pardon my ignorance. Any insight or recommendations you can provide for a noob on what to check next and proper steps to take would be much appreciated. Thanks!

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Fortunately I do have the original manual and honestly, it’s hard for me to decipher a lot of the wiring schematics since I’m brand new to this... Will continue to do some reading and learning on the proper wiring and working back. As for the fuses, I pulled them up and used a multi tester set at 200 ohms. Do I do the same for the coils, referencing back to the manual on what the correct ohms should bring? How do I test the transistor?

Thanks guys. Last night fired the game up, and both left flippers worked fine for about 5 minutes then cut out. At first I thought when the coils or connections heat up, it shorts out and that was the root cause. So I Raised the Playfield and checked both left flipper coils... the left upper tested out at 6.0, the bottom tested out at 4.5. Rechecked all the connections, ran the factory diagnostics tests then fired it up and it worked completely fine! Played for a good hour with no issues.... leading me to believe now there’s probably a bad cold solder, or more likely a bad ground. I’ve read these system 3’s are notorious for crummy grounds and they all link up to the power supply. For now, I shut off the shaker as that’s what initially caused the short and do far it’s been playing ok (fingers crossed) Any insight or recommendations on next steps would be awesome. Man, these things are intimidating for noobs!!! Thanks again!

Can you please elaborate in more detail?