While it is possible to upload files to both models from an external source it is not possible to copy them from one of these models, unless they were imported first.

The drives are the same.

One problem that has existed for some time on Humax freesat recorders is that the timeslip buffer is constantly reused and this will cause constant use of the same disk area. Defective sectors within the file can cause loss of buffer functions, however where the write succeeds after a several retries, this can cause picture distortion. This is due to the writes being performed by an interrupt routine, normally non maskable, which means it has priority over any other tasks.

Do you have the lines when you play back a recording or watch on-demand?

anonanymore – 1 hour ago  » 

Pulled the plug on the machine overnight, problem disappeared.

Lines appeared on recording playback but disappeared on fast forward/reverse, then reappeared on normal playback.

do they occur on on-demand?

As it it not possible to transfer recordings, I suggest you try a disk format before you ditch the unit. Many hard disk errors can be structural rather than physical. It is worth a try.