Replacing the cables is on my to-do list. They all need to be replaced as some are cracked and as you mentioned there is some corrosion at the connections.I noticed the corrosion under the insulation of the cables. I would also replace the cables because the corrosion will cause high resistance in the system. Also, your car should have 2 batteries and a dual battery switch, so you can run on one battery in a parade and then have the other fully charged battery to start the car. The battery switch will have battery 1, battery 2, and both batteries, along with an off position. The switch was manufactured by Cole Hersee Company in Boston MA
There is an Amp meter gauge on the console below the siren, but it does not work....it's on the list.No warning light on a pro car. One would need to put in a amp meter gage. The duel belts were a safety factor.
Engine on/offMost likely the amp meter is working, but just doesn't move very much. With the engine stopped, and the key in the on position, pull out the headlamp switch and note is there is movement in the amp meter. It should move slightly.