In the absence of any further advice, I've decided that the easiest strategy is to use a dual SATA docking station to clone the HD from TiVo 2 (OzTiVo mod, software 11.3b10, 2TB drive, MAK key) to the HD of TiVo 1 (OzTiVo mod, software 11.3b8, 2TB drive) and then re-install the HD into TiVo 1 and do the full Guided Setup with Clear and Delete.

There's nothing recorded on TiVo 1 that I need to keep. I'll also backup (TBK) TiVo 2 to preserve the MAK in the event of any problems removing and re-installing the HD from TiVo 2. I understand that the MAK won't transfer to TiVo 1.

I'd welcome any advice regarding flaws in that approach.

Regards
RLSA