Update of weirdness:
Went to the bike with the good battery. Went ahead with testing the starter: removed the plastic cover over the starter to access the connectors, to run a wire from the spade connector on the solenoid to battery Positive.
Access to the connectors was still limited, but I noticed a spade connector not fully engaged on the solenoid(?). It is a thin wire and appeared brown. Do you guys know if this is earth? It seems incredible thin.. A picture is attached.
I seated the wire well and thought lets see…: hooked up the battery and… it started right away. Had been a full year, but really only 2 seconds of cranking. More amazing was that the head light (that used to stay on after switching of ignition) turned off normal. Also the neutral light functioned normal again.
Went for a drive and all was fine. One time it did not start (it primed, clutch switch reacted and neutral light worked), nothing. After 1 minutes it started right up again.
So… depending on what that wire is: could this cause the headlight staying on issue, neutral light not illuminating and non cranking - in your opinion?
Cheers from a still somewhat amazed but happy guzzi rider
Vins