Dear Mrs Bretter, the problem is most likely assocaited with you changing your brand of discs. If you use the rewritable disc shipped with the unit in the drives not being recognised, does it work? Kind regards.

We have been using the same discs all the time and had no problems up until recently

Pls advise what brand of discs - we can maybe send you firmware update. I will ask a colleague to forward.

We use HP CD-R printable.
The second machine has started making the same problems - the duplicator doesn't recognise 2 drives. On the first duplicator another drive has stopped working.

Pls try alternative media, and reduce the burn speed. It is unlikely for 2 machines to suffer the same problem at the same time with hardware failure. Kind regards.