When you have a lot of time then you can spend it by finding the right solution for this problem. In my opinion there is only one I would check.
1. Do I have a backup of the data of the defect HDD? Yes then put the bad unit in the garbage and replace it with a new on.
2. When you don't hv a backup and there is no chance go get to the data then read 1. and replace the unit.
Thats the fastest way.