I just went into the menu options. Restore Factory Settings opens a screen which says "Warning, this will delete all of your recordings" - Restore or Cancel boxes offered. I cancelled.
Perhaps I will pop out the hard drive and copy the recorded files and then restore one of our units. In the meantime I will attempt to leave them on at night. I will change the auto switch off to 3 hours and put them on at 11pm.
Fingers crossed
Rans6....................................................... ....