Hi All, pretty new here, looking for some help with a Stargate pin. I am pretty new to the ownership/maintenance of pinball and was looking for some help. I was given this machine about a year ago and up until recently it had worked fairly well. I tried to play a couple of rounds and log out the behavior in hope that someone here could help. I saw a few related threads but the issues are not quite the same. Appreciate if anyone could help point me in the right direction. Note that I DO have the manual for this, but honestly didn't even understand where to start there. Look forward to learning more here as there are quite a few small things this machine also probably needs. Also apologies if I got any of the terminology wrong.

Current Behavior:
- Power Up
- Press start once
- One ball comes out, auto plunger doesn’t activate and you have to manually plunge the ball (normal)
- Play goes as normal, but once you hit a multiball, another ball goes into the shooter lane and auto plunges. Then, a few seconds later a new ball is added to the shooter lane and auto plunges (usually it was just one, and the auto plunger never worked until this all started, see notes below). While you are playing with 3 balls, if one ball is lost, the multi ball music ends as if there is only a ball left (2 are still left). Once you lose another ball, then the table stops as if you’ve lost all the balls even though there is one still in play. Since the flippers stop working, that last ball eventually just goes down the middle.
- Once the above step is completed, a new ball is put into the shooter lane, this time, it auto plunges into the playfield. About 2-3 seconds later, another ball is dropped into the shooter lane and again, auto plunged into the playfield. If either of the two balls is lost, the turn is over and the other ball eventually drains.
- Start a new game, now, whenever a ball is pushed into the shooter lane, it is auto plunged into the play field. It seems like once the machine is warmed up the behavior changes. Usually, a second ball is also auto plunged into the play field. At this point the the game becomes unplayable and balls end up getting stuck somewhere in the top of the playfield until either the turn, or the entire game ends. Once it ends, a drop target drops and a ball that was usually behind it drains.

Notes:
- Previous to this, I had the table glass off and the table tilted up to try and replace some leds.
- Also previous to this behavior, the auto plunger rarely worked, so if you got a multiball, you had to manually fire it into the playfield or it would just sit in the shooting lane. The game however worked fine.
- I also made sure the tip of the plunger was on tight.

Thanks in advance for any help/ideas on this! Please let me know if any other information/photos would be helpful.

Thanks both of you for the feedback. I did check and there were 4 balls total, nothing changed there since it was previously working well.

I'll go through the diagnostics and tests in a few days when I have a bit of time and follow up on that.

Finally got around to working on this. If I could add a facepalm, I'd put it here, zacaj it turns out, there was an extra ball installed, so after removing that, things went mostly back to "normal". I'm not sure how it worked before for nearly a year, but the only thing that I did when the behavior chagned was to raise the playfield out of the table to look underneith. Not sure if a ball was stuck somewhere and got jarred free, can't explain it.

PinRetail Back to the "normal" behavior. I'm still seeing some issues with the auto plunge (I'm probably calling this the wrong thing?). I played a few games and what I noticed is:
- Occasionally the first ball will still auto plunge
- Most of the multiballs need to be manually plunged. Occasionally, one of them will auto plunge, but maybe 1/20 times.
- After starting a new round, sometimes before the ball is put into play, the music changes as if the ball had gone down a particular area. I left the game sit with a ball in the shooter lane for a few minutes just to confirm the auto plunge didn't go, maybe this is expected.

I did run some tests, and the switches that were showing issues were
05 - Tournament
21 - Glider Motor Stop
24 - Outhole
34 - Trough
35 - Rollover Drop Target

From the behavior, it seems like 24 and 34 might be my problem switches? Is there anything in particular I should look for here? Or should I go ahead and order them? I see them available on a few different sites, any one of them in particular preferred by pinside members?

Side question, I have a few other issues that I'd like to look into, several smaller issues (pop when turning on, power supply, etc...), should those go one per thread? Or can a few smaller issues be bundled together?

Appreciate all the help and suggestions!