If you're stuck and Mark from Berry can't help you out West, shoot me a PM can put you in contact with someone.
Long story cut short...
My old head unit from the 1988 BMW E30 is an BMW branded Alpine unit.
Out of pure luck, called into the Service Dept at Alpine H.O. here in Vic to see if they could fix it.
An older dude in the workshop overheard me and knew all about that radio and which car(s) they came from.
A few days later had a fully functional head unit good as new.