I've been told that the Airflow meter on my 2002 Td5 Defender cannot be cleaned, & HAS to be replaced with a new one. All I can see inside mine is 2 fine wire posts that I assume to be the sensors. I've put in a new one, but as I spend a lot of time travelling in dusty conditions, I thought I would hang onto the old one in case it CAN be serviced. Any thoughts on this?....Regards Scotty