You likely thought of this, but..
The old 1amp slow blo fuse issue?....maybe under the playfield in the vicinity of the ball in play kicker?

I have little experience with Williams, but this is common on that generation of Bally.

There is no separate playfield fuse on Williams games.

Does the outhole solenoid work in test mode? With ball in outhole? And what do you mean by "wants to kick out ball"? Is the solenoid partially operating?

It sounds like the game does not know that there are two balls in it. Can you remove the apron and confirm that both trough switches work in switch test mode? (You don’t really need Leon’s test rom once the game is booting.). While in there, make certain there are no physical problems clogging things up. Both balls should be in the trough, one should NOT be in the out hole.

Another common issue is the start button may not be registering. Confirm it works in switch test as well. Also check the out hole switch is registering every time.

It’s also worth mentioning that it is also
Important to check there are no EXTRA switches closing that should not be, while in switch test. It’s so important and a lot of people do not realize this.

I’ve owned a few Sorcerer’s and these two things were actually a problem on both!

So you went into switch test and the machine is reporting ZERO switches closed with the balls removed. In other words, there is no number displayed on the credit/match display in switch test with the balls removed?

If that's a yes, then load the balls, then manually push them over to the trough area and go to switch test and report here what two switches are showing as closed on the C/M display.

I do realize you went into switch test and that you understand how to use it. Obviously there is still something wrong. The Pinside technical help portion of the forum is a public message board where you ask for help. It is not just for you, it's for all pinball enthusiasts to learn and understand, for all time.

One strange thing you mentioned above "the drop target coil" resets. Sorcerer does not have a "single" drop target... What mechanism are you referring to that "resets" when you press start? Also, the "multiball eject" fires... that's not correct. It would only fire if the game is missing a ball or that multiball eject switch is tripped.

One other thing to try in switch test is when nothing is tripped, bang your closed fist down in the middle of the playfield hard and make sure that no switches are being tripped. That could help point out one that is adjusted way too close.

Sure it does, a three bank, upper right.

Does the kicker assembly move freely? Could there be some binding in the coil that is hampering it enough to not be able to fully eject the ball?

Sorry, I was thrown off by "drop target" (singular) was thinking you meant a single target.

After reading your most recent post, as a next step I would replace Q48. I know, I know it works in test mode. I have had TIP102 and TIP122 transistors just beginning to fail and they only work under certain circumstances.

If that does not resolve it, if you have one, I would swap the ball serve coil if that does not help, then swap in a known working system 9 board into the game to try and confirm it's the driver board that has the problem.

As an additional test---> (You could also take a bare wire and hold one end to the side rail of the cabinet and the other to the TIP102 at Q48 and see if it fires when the game is in attract mode. I would only do this very briefly and only a couple times as you don't want to blow the fuse.)

Some other thoughts, the problem is only happening when the game is in a specific state (attract mode). So, we have to determine what is special about that state. Just spit balling, a bunch of lamps are on in attract mode, the displays are in a different state, and the sound board trying to fire up... So, we have those three things drawing power that are not in the same state during the coil test mode.

Also, the drops are supposed to reset when you press start but the multiball kickout coil is not supposed to fire when you press start. It would only do this if the game thinks a ball is missing.

It sounds like you are getting very close, just need to dig a bit deeper.

Are any error messages displayed after pressing the start button? I had a Bally Party Animal that previously wouldn’t start a game. When pressing the start button the display would say PARTY! PARTY! PARTY! PARTY! A ball would correctly eject but then immediately the game would stop and it said error check playfield fuse whatever. It ended up being a misaligned ball serve plunger arm that wasn’t resetting so the game thought the coil was locked on.

There are no error messages displayed on system 9’s...

And the coil fires with a jumper wire? Sounds like a mystery to me. I really don’t know at this point. Did you try to unplug lamps and sound board, displays, etc, and see if the game starts with the bare minimum connected... (switches and coils only)

I also wanted to confirm the game does go to “attract mode” correctly when it boots?

The only thing I can think is that the test part of the roms are working but the game parts are not... maybe tone out the socketed EPROMs and make certain a pin is not missing (I know you tried different rom chips).. look with a high powered flashlight and make sure that a socketed chip has no pins bent or missing... (tone out ram socket too). At this point I feel like a trace or socket is faulty.

Maybe take your system 9 board to a friend or location with a system 9 game and test it in another game as a last confirmation that it’s the board.

If you figure it out, please Post the fix. It’s a strange one.

Good that it works now!

Could you give a download link to both romsets, so we could try to find out why the other one did not work?

Wow, ok that is good you got it going. I would post in the Sorcerer Club those roms don’t work.