Went for it & it worked. Put the drive back in the bad enclosure & sure enough there it was on restart. Let Drivepool settle down then removed the drive from the pool with duplication later. Took 2.5 hours to remove a 3TB drive. Powered down put it in the new enclosure (with fan) & used Mini tool Partition Wizard free to re-partition & reformat. Added it back to Drivepool & its balancing away. I'm out one cheap enclosure & not a $100 drive or 2.5TB of data. No short way around I could see, took most of a Saturday afternoon while I watched my college team get pummeled. But that's another story. Hope this helps out someone who swaps USB enclosures or moves a drive to internal get out of jam & get their data back. Found an old post where Christopher made a suggestion to a poor soul with the same problem as me, worked both times, so thanks Chris for helping without even seeing this post.
dslabbekoorn's post in USB drive turned GPT protected after power outage was marked as the answer