Hi my unit has started to sometimes take an age to come on displaying "sat nav Initialising" before eventually working. If you try reinserting the disc it gives a disc unreadable warning. The disc I am using is genuine audi so I think the problem could be a dirty lens or even the heat as it is worse on hot days. I am happy to remove the unit but can someone tell me how easy the lens is to clean with regards access etc.and how to do it. I thought my first option would be to clean the unit with compressed air and use alcohol swab on the lens.