Test the driver transistor first with a DMM. Grounding the transistor tab only tells you that the wiring from the output of the transistor is good, it does not test the driver transistor

Schematic Pdf download link from Ipdb.org:
https://www.ipdb.org/files/1970/Williams_1986_Road_Kings_Manual.pdf

That PDF is incomplete. In fact ... it's a stitching of two different manuals. The master AN board page (50) is from Road Kings. The CPU parts layout and sheet 1 of the schematics is from High Speed. It then skips sheet 2 of the schematic (the sheet you're looking for) and goes to sheet 3 from Road Kings.

Try downloading the High Speed manual. You can actually download any System 11 manual. The solenoid section of the schematic did not change during the System 11 life cycle.

Haha, i just did the same thing as DumbAss suggested--here's Q23:

Screenshot_20210213_151906_com.google.android.apps.docs(1).jpg

This is all you need to know right here. It's a CPU issue.

Yes, you should buy one, it's a very inexpensive tool that can use the rest of your life.

You don't really need a probe, you can use a voltmeter or DMM. You can see steady logic hi and low, and brief transisions. That's all you really need to troubleshoot the solenoid circuits.

Check at the points indicated with a pulse symbol in the diagram when in switch test. You can use a voltmeter for this. A logic probe is nice but not necessary. I've been in professional electronics for 40 years and haven't needed one or owned one. My go-to is an oscilloscope for anything required beyond a DMM for pinball repair, even then bringing out a scope is very rare.

Forget about the AC relay. Unless you are having problems with a bunch of flashers and controlled solenoids, that's not your issue here.

Does the sling coil kick in either test mode or gameplay at all, or just when you ground the transistor tab?

Screenshot_20210214-171336 (resized).png

Ok. That is controlled solenoid #6, and is a different diagram (below). To divide and conquer, I would look at pin 11 of U19 for a positive pulse during test. You can use a logic probe, oscilloscope or a decent DMM/voltmeter.

Screenshot_20210215-045540 (resized).png

Now check for pulse activity at predriver Q19 emitter during test (which is the same point electronically as Q23 drivers base)

Test and or replace Q19. Note that it is common to replace predriver transistors automatically if driver transistors are blown. There isn't a whole lot else between where your pulse is and the driver. A couple of pull-up resistors, that's about it, and you can check those too before replacing anything. You've basically got the problem cornered.

The difference between those transistors are negligible, as far as pinball is concerned. For the pullups you can just take measurements between a nmknown good controlled solenoid circuit and your failed circuits, because the controlled drive circuits are the same. You can take resistive measurements in ohms with the circuit power off and/or voltage measurements with the circuit energized.

I thought you checked the pulse at U19 in a previous post. Glad you got it working.

Glad you got it fixed!

Playball!