Migrating Disks from NV+ to NVX

Hello Folks,

I'm new here ... I have / had an old NV+ NAS with four 1TB drives. I hadn't used it for years and when I got it going again the other day, all was well for a few hours, backing up my MBP with TimeMachine, until - I'm guessing here - the PSU failed mid-backup, tripping the ring main breaker; the plug fuse (13A!) is Ok and it won't restart.

Rather than try and repair or replace the PSU (my regular MO), I decided to buy a used NVX complete with disk trays - looking forward to the performance upgrade! So I've moved the four 1TB drives - in order - from the NV+ to the NVX and powered it up 'Normally'. Error message says that it can't mount the RAID disks ... Ok, so I boot into 'OS reinstall' mode, which seemed to be Ok until the same error message appeared. Any clues or ideas how to proceed? I'd really like to retain / recover the data on the RAID set.

I haven't yet tried connecting over the network ... will try this next and see if RAIDar can see it.

Many thanks in advance.