My 147 is currently at Guest Alfa Romeo in Knowle (previously Ryauto). They have a printout of the document from Blaupunkt and insist they have never heard of this problem before. In fact, they insist that the document refers only to head units from the 156.
I gave them the document and the serial number of the head unit 3 weeks ago hoping they would contact someone somewhere and get all the replacement parts ordered ready. Yeah right.
I had to explain the symptoms yet again.... and now they will "see what they can find".
I doubt they'll ever even admit that its a problem, never mind actually sort it out. I guess I should just do what the Blaupunkt document recommends - find a Blaupunkt service centre.
I'll keep my fingers crossed and let you know...