Looking to replace the Concert cd/radio with another from ebay - want to maintain std look so i know I'm running the risk of having more poor quality Grundig volume problems. Seen lots on ebay, but do I have to get one from another A4, or do the Concert units from all the models A2, A3 etc all fit the same sized hole??? One sold earlier from an A2 but it looked narrower than the A4. Can anyone help please??