What is the fine-grained topic of the following text: ..so the Main AC ground was hidden except when viewed from the black tank area, loose and corroded, practically useless - I suggest you renew the hardware there and use an anti-corrosion compound, I have a tiny tube of "NO-OX-ID A Special" that's made for iron as well as copper and aluminum and is conductive (therefor do not use it anywhere it might creep across and complete a circuit, just grounds or buss bars etc.. Only return the topic.
Maintenance and repair suggestions for an AC ground connection