I'd download and use the manufacturer's diagnostics on the 'bad' drive. If it passes, try to restore your backup to the 'bad' drive (due to quirks in mfstools it may not restore). If it does restore successfully, but the system does not work you will have to do more troubleshooting. If it does work, you will have to either run 51killer or do a Clear and Delete everything.
If it fails the diagnostics, you have two possible choices - buy a new drive (I'd suggest a larger drive) or test your existing drive in the new system. Another option is to try the 'bad' drive in your existing system.
It's your money; rather than spend $20 for Instantcake, I'd suggest spending the money to get an even larger drive.
There's a difference between needing help, and just being plain ole' lazy.
"You cannot teach a man anything. You can only help him find it for himself." Galileo Galilei (1564-1642)
HR20-700 with 2 TB, HR22-100, HR22-100, HR22-100, HR23-100 all running 0x5cd and networked.