Ready NAS hanging

I've read about not swapping drives after doing it.

My 4 disks are

Hitachi HDT725032VLA360

300GB, 3.5 years old.

Now it is doing an automatic resynch.
It was going pretty fast, then at 60% it has slowed down massively, and I can hear a noise: I guess from one of the drives, but I have no idea which one.

PapaBear wrote:

1. You should not sent the logs to Negear unless a tech or Jedi asks from them. They are generally sent directly to an individual. 2. It is not a good idea to swap drives around in the NAS, especially if one or more drives is throwing errors. That is a good way to lose the entire array. 3. Generally, when you first begin having problems, the best first thing to do is to create/update your current and complete backup. With a complete backup, if you lose the array, you still have a way to recover your data. If you do not have a current and complete backup, create one now before you do lose the array. (I lost one Wednesday because two drives had a problem in a 3 drive array. However, since it was the second backup of critical/important data and the original and backup are intact, my data is secure.) 4. What are the make and model(s) of the drives?