Migrating data from ReadyNAS Duo to 214

My old ReadyNAS Duo is dead, sadly, though the redundant SATAs inside are fine. 

I need to transfer the data from the old, but good SATA retreived from the old ReadyNas Duo and tranfer it to my higher-capacity new SATA(s) inside the ReadyNAS 212.

I've tried a Sabrent adapter to retrieve the data off the old SATAs using my PC to no avail.  Apparently the filesystem is different.  Sabrent requires an initialization that will not permit me to access the data on those old SATAs.  Not sure how to get the data off the old disks and onto the new ones.