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Intermittent Drum Switch Operation

Reversing a DC motor while it's running, by changing the polarity of either the armature or field, is called "plug reversing". If you do it at full speed it can damage the motor. The AP (Anti-Plugging) relay prevents you from plug reversing the motor.

You can bypass the AP relay by connecting between these two terminals:

Do not use either of the coil terminals on the side! It would be cleaner to connect to the terminals on the back of the panel.

I now see why your AP relay isn't working. The braided copper wire is not original. The original wire was tinned copper and connected to the moving contact arm via a small hole at the top of the arm:
View attachment 394236
The original wire appears to be soldered to the arm. Without the wire, the AP relay won't operate reliably.
Not entirely clear on what you are seeing. Here are better photos of my wiring and contacts. The unraveled bare copper wire appears firmly connect to the arm.

If I can get the rely working reliably by rewiring, I sure rather do that than bypass it.


AP Relay Wire Connections 1 04-23-23 640.JPGAP Relay Wire Connections 2 04-23-23 640.JPGAP Relay Moving Contactor 1 04-23-23 640.JPGAP Relay Moving Contactor 2 04-23-23 640.JPGAP Relay Moving Contactor 3 04-23-23 640.jpg