Rdxv60kb dubbing issues?

Hi there, I have a Toshiba RDXV60KB HDD & DVD Video cassette recorder which has been used frequently and has been very reliable up to recently, that I use to record craft programs and then the ones I want to keep, record these from the HDD to DVD. Lately the recordings, from the Dubbing menu, have been stopping with error codes suggesting that the DVDs are faulty. It is a bit hit and miss making the recordings but it is wasting disks. I have been deleting items from the dubbing list and then setting the dubbing to start again so the disks can't be faulty can they if the recording continues on the disk. Can someone please tell me if I need to have a repair or is it probably faulty blanks disks? Also is it possible to do a software update for it - if it needs one?