This is from the Mission UK site's FAQ:
"Mission endeavours to carry a comprehensive range of replacement parts for many years covering both current and discontinued models. Typically, these will include spares items such as tweeters, woofers, grilles, plinths and foot spike sets. Please contact our service desk on +44 (0)1480 452561 or e-mail to spares@mission.co.uk for prices and availability."
It would be worth an email to them to see if a driver is available or if they will tell you the model of the driver. It might be available from someplace in the U.S. like Madisound or PartsExpress.
"Mission endeavours to carry a comprehensive range of replacement parts for many years covering both current and discontinued models. Typically, these will include spares items such as tweeters, woofers, grilles, plinths and foot spike sets. Please contact our service desk on +44 (0)1480 452561 or e-mail to spares@mission.co.uk for prices and availability."
It would be worth an email to them to see if a driver is available or if they will tell you the model of the driver. It might be available from someplace in the U.S. like Madisound or PartsExpress.