On a side note I know you said the grounds LOOK good, but lessons learned tell me to remove the grounds-- use a bonding brush too clean the metal then reinstall ,they could have painted before installing them(high resistance ),very common issue on Agusta Westland products also
Keep us posted on what you find.. here is an older wiring diagram
https://drive.google.com/file/d/1E5K...usp=drive_link