So, ever since I bought my Stargate, I've had an issue where, after a little bit of play, the left flipper becomes noticeably weak enough to the point where the right ramp shot is extremely difficult. I tried a few different things in an attempt to fix it, and while I was able to improve it somewhat, it still eventually becomes too weak to make the shot. The other day though, I realized that the issue might not be the flipper, but it seemed that other solenoids become weaker too. Left ramp shots from the upper flipper become harder, and the auto plunger fails to send balls all the way up the ramp more frequently when the game is played for longer. With this in mind, I tried a couple things.

First I cleaned all the relays in the bottom of the cabinet, something I haven't ever done. Of course, they were filthy! Now, I'm not sure If it's just me, but it almost seems like that made the issue *worse*. Whereas before I could usually play a couple good games before the right ramp became a struggle, now it seems to happen way faster. I don't know how cleaning the relays could have had such a negative effect, or even if that was the cause, but now I'm more desperate than ever to get rid of this issue once and for all.

One other thing I tried doing was swapping out the factory installed 110V red jumper in the transformer panel with the 120V orange jumper, as pinrepair.com says you should do. Doing this seems to cause the solenoids to start out weaker. I have yet to see the auto-plunger successfully send a ball all the way up the skillshot ramp with the 120V jumper installed. It can do it just fine for the first few minutes with the 110V jumper installed.

As a final note, I have not done grounding mods. They seem a bit complicated and other than this issue, the machine has been working just fine so I haven't really felt like they were worth doing. Unless, of course, doing them will fix this issue!

So, with all that said, what should I do next? What should I be checking to ensure the proper amount of power is being delivered to the solenoids? Any parts on the boards or power supply worth replacing?

Got it, thanks. I'll get to work on the ground mods tomorrow since I have the day off. Any recommendations on which method to use (pinrepair.com suggests two different ones)?

Alright, I completed the grounding mods! After a little bit of testing, it seems like the issue still persists, but I'll do some more testing later to make sure. On the bright side, it seems like it fixed a couple of very minor issues.

So, any suggestions on what I should do next?

Hmm, so I played for a little over 30 minutes, and now I'm not even sure if it's all the solenoids or not... The upper flipper didn't seem to have any issues, and the auto plunger had about a 50/50 success rate. The left flipper still remains the most inconsistent though. About 15 minutes in it seemed like the right ramp became impossible, but every so often I could still make it somehow. So either the issue is isolated to the left flipper, or the left flipper is just the only solenoid that you can easily tell is weaker since the ramp shot is so far back and so steep...

Anyways, the lugs on the left flipper seem fine to me. All the fuses look good and tight too.

IMG_0248 (resized).JPGIMG_0249 (resized).JPGIMG_0253 (resized).JPGIMG_0255 (resized).JPG
48v bridge rectifier

So I'm assuming the only options I have left are to replace the bridge rectifier and/or the left flipper solenoid?

wayout440 That's a good idea, thanks. I checked the EOS on the left flipper with a multimeter and there actually is a very small amount of resistance, whereas the right flipper's EOS doesn't seem to have any resistance at all (And is also noticeably cleaner). The resistance on the left EOS didn't seem to change at all after a few minutes of play. The flipper button switch shouldn't be an issue because I just replaced that switch about a year ago (The old switch had a holed burnt through it and was missing the disk capacitor), although it does look like the new switch is starting to oxidize a little bit.

Anyways, I tried cleaning the EOS with a business card and then a file, although I'm not sure if I was using a good file because it didn't seem like anything was coming up. It didn't seem to help much, but again I'm not sure if the file I was using was fine/rough enough.