The dealer with being so new could not get a service manual as they are no longer in print so the best option was to send back to Bang & Olufsen service in gloucester,
Unfortunatly due to the age of this product the parts are no longer in stock, ( keeping parts in stock up to 10 years after the item has seased production ) The cost of £50.00 will be for insured collection and delivery to gloucester and for the engineers time to open up the amplifier and test it to locate the problem and then to put back together.
Derby have an enginner who has serviced Bang & Olufsen for the last 10 - 15 years and as long as he can get the service manual and the parts can repair pretty much any product.