This fault occurs when recordings accumulate on the hard drive. If I go to my list of deleted programmes and PERMANENTLY delete them, then the fault clears. The fault begins to occur as broken audio then quite quickly becomes complete loss of audio when the Drive still has only a small percentage of its capacity in use. I have about 1.2TB of record space.
I can't think of any reason why this could happen on only one of the tuners and affect only TV!.