Yes that had occured to me as well.
But as I am FI I tend to tread a very careful line with the engineering types. Telling them how to do there jobs etc.
But as they seem to have run out of ideas I though about using pprune.
Next time its down I will see if they will let me run it up with another FI with the cowling off and take some readings with a voltmeter. But as with my car electrics its more by luck than judgment if I come up with fix.
Thanks for your input
MJ