I had the same prob. as Diamond Dave - aerial fouling on up and over door. I sourced a new one from www.rockshore.uk.com of Ashford Kent. It is an Autoleads Vauxhall aerial replacement mast part number RMA883, length 284mm. It is important to choose the correct fitting - M6 NOT M5. An M6 screw is 6mm in diameter (10mm spanner). The Autolec one has a brass core and provides excellent reception. Cost £8.95 plus £1.99 p&p.