I have the security code for the CAR300 cassette player for the 1997 Astra I just bought, but I can't get it to input. I had to remove the deck to clean it as it wasn't playing properly, and I've read the instructions that say you have to press AS for 3 seconds while switching the unit on, then the code entry starting with 10 _ _ _ _ will come up in the display. But pressing AS does nothing, It displays SAFE immediately and pressing AS doesn't change it. I've tried this a dozen times in variations including disconnecting the unit entirely then reconnecting followed immediately by starting the engine, pressing AS, and switching on the unit. Keep holding AS for minutes and nothing happens. Still just says SAFE. Anyone got any ideas? It was working before I pulled it out yesterday, so it's not that the code has been entered more than ten times - I haven't had the opportunity to enter it once! TIA