Hi Bill,

The special solenoid circuitry on all System 11 MPUs is in the upper right corner. You'll see 6 TIP-122 transistors there, arrayed 3 by 2.

Here's the relavent part of the schematic.
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Bill

What you are talking about is typically mounted across a special solenoid coil, not on the driver board, on a system 6ish era game. Off the top of my head, these are not on sys 11 games.

When i have solenoid problems, and i am sure the pre driver and main driver are good, i pull the solenoid fuse and test in a game during solenoid test. Focus on the outputs of the logic ICs. Look for a stuck or floating output.

You can also find bad logic ICs like 7402/7408 on with power off board pulled. Red lead on ground black lead on suspect output (and in). You should see normaly .600ish. Around 200 or below you can be almost sure it is bad.