Hello and be welcomed to the forum.
Are you sure that the drive that you are attempting to recover have bad heads/pre-amp ? Did you test with terminal and confirm head damage ?
Also swapping the head stack by yourself it's not a good idea, unless you already have practice doing so.
Are you using a laminar flow bench ?
Remember that if the answer to the above questions are "No" then you will make your drive unrecoverable even for a data recovery firm.
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