Hi Scaro
Thanks for the update. Don't know if it'll help but I've recently been working on an installation with a mis-behaving ADF which started working again after we changed the suppression capacitor on the alternator and re-adjusted the voltage regulator. Although in an ideal world the ADF shouldn't be bothered by such things, it might have been sensitive either to alternator noise or incorrect bus volts. Might be irrelevant in your case, but both things are fairly easy to check.
Regards,
B.