Lost 12V Ground 1 circuit Interior Lights, Ideas on finding

Found the grounding problem / location.

Ring terminal that attaches to grounding plate on the MH Frame rail was not attached. Not only this one, but there are 12 ground wires with ring terminals that connect to same 3/8" Bolt. 9 out of the 12 basically fell off as i was checking them. Corrosion is the culprit.

Really a blessing in that by the number of miles I'll be putting on the vibrations etc from the roads would have caused the others to have failed.

Now tomorrow I have to find some either at Lowes / HD or Grainger.