The whir and clank is not encouraging. I'd leave it alone and take to an expert if the data is (are) that important.

At work, the IT guys have had to send drives out to be recovered (mostly from remote workers who don't have the best backup environment or discipline). I'm not sure which service they used and can't make a recommendation, but there are are few big names. At least one data recovery specialist sponsors public radio, I think its TechFusion.