What did I overlook?

[Lumpy Rider]

Hi all! Been 9 months recovering from heart stuff and job stuff and rebuilding life so "Ruby" has been collecting dust and needing TLC. i am now back in the saddle! Aside from performing all the usual maintenance, I pulled the air box to sync the carbs (sorely needed) and replace plugs and found disintegrating positive battery cable and destroyed #2 spark plug lead (the plastic boot was shattered up to the terminal and not making contact with the plug). She runs grrrrrreat now! One problem is the temp gage is no longer functioning. Any ideas what I overlooked reassembling Ruby to cause this? Your ideas could save me time. Hopefully, I do not have to pull the air box again. Thanks!

[Neill004]

You will find that it's the earth connection point. This is accessed by removing the battery and battery tray.