I noticed that 5th and 6th were a bit noisy earlier this year. Thought nothing of it, but decided close to Xmas that it was definitely getting worse, and that I ought to act, given my 3rd year warranty expired in May this year.
Popped into Guests at Willenhall on New Year's eve, and got taken for a test drive. Immediate decision - "Yes that's not right, we will speak to Alfa UK and get a replacement gearbox authorised"
The new 'box was authorised almost immediately, which was just as well as 1st and 2nd got really noisy over the New Year period.
The car went in yesterday, and I picked it up today, complete with new gearbox.
Result - one very satisfied customer, so well done Guests of Willenhall and Alfa UK.
I got the impression from Guests that 159 gearboxes don't fail often, so mine may have been a one-off, but I am very happy with the service I got.
Sorry this is a boring post, but we need to remind ourselves of the good points of Alfa ownership. This is after all the only problem I have had in 45,000 miles.