Failed to crank over after NSS wire wore down?

Thanks so much for your reply, Ken. Yes, the NSS wiring was repaired, at least to the point that the truck would start. The shop that replaced the 40-amp fuse fixed the NSS wiring so that the starter would fire. And after this the starter would sometimes start but also fail intermittently: sometimes it would only fire after 2-3 cranks (silence otherwise), sometimes I'd have to let engine cool for the starter to fire.

Is it incorrect to conclude that if I hear the starter solenoid click once when I turn the ignition key that the solenoid trigger wire is getting enough power? I'll need to check it later when I have a voltmeter to know if it has the necessary 12V.

At this point, the battery should charge, but the Rally 2-amp maintainer connected as in the photos, doesn't indicate either it is charging or that the battery is bad. I tried several different connection points to get a good ground with the same result. So, there seems to be some other electrical issue.

I very much appreciate your assistance.

Yes, but the instructions for this Rally model say not to connect the charger directly to the negative terminal. If the battery is installed, the negative lead is clamped to the chassis, engine block, or other ground; but that setup wasn't working so I disconnected the leads and tried to get a ground through the negative cable.

It's working now. With the battery uninstalled, the negative lead gets clamped to a 24 in. (Minimum) 6AWG lead wire connected to the negative terminal (instructions photo - Step 5 in the “Uninstalled” section). The charging indicator is on now (see photos).

If the truck still doesn't start after topping up the battery, I'll check the starter trigger wire voltage. Thank you, Ken.