is the dvd burner tray or slot loaded. if it is tray loaded then you can try a cd lens cleaner other than that you can always try seeing if you can update the firmware on it if you run out of options. other than that i don't think there is any other way to get the drive to burn DL disks right again. DVD-DL burners can be found for under $30.00 these days anyway
You are about to answer a thread that has been inactive for more than 6 months. If you still wish to proceed, please ensure that your posting is original and does not duplicate or overlap any prior responses to this thread.