I emailed a chap who advertises on eBay and for £35 they will repair any 300 or 660 series nuvi with a three day turn around.
I had explained the problem I was having both to Garmin and to a few forums but none seemed to know what the problem could be, on the other had I emailed this guy and soon as I said the problem I had he said that it was a common problem and that I needed a new arial. They would also sort out the software as well included in the price.
If you go to eBay UK and search for Nuvi the link will come up.
Mine is getting sent off at the end of the week and will be back by Thurdsay at the latest.
Sam Graham
February 2009