If it is indeed important data, I wouldn't mess around - especially if it is a case of mechanical failure.
The way you phrase your question makes me assume you are not a professional in data recovery. So, without meaning any offense, I suggest you immediately stop doing what you are doing and approach a professional company for the recovery. (It will cost a fair bit, but it is a logical consequence of not backing up. The cost you save one way will be incurred in another.)
Every action you take (even just turning the machine on) increases the chance the data cannot be recovered even by specialists.