Medium Changer not detected in Windows 2008R2

Hello. I am running BackupExec 2010 R3 on a Windows 2008 R2 server with an IBM TS3200 tape library, which has been working for well over a year without issue. Now I am getting these errors in Backup Exec and my jobs fail:

Physical Volume Library Robot not found

I have done some investigation and it seems it is because there is a device missing from Device Manager named Medium Changer. Does anyone know how I get this back? I can't get it to detect, although the LTO drives within the library appear fine. Help needed please!