Physical repair of a hard drive is best left to the professional data recovery companies. An excellent and (by data recovery standards) reasonably priced option is
http://www.gillware.com/However, if you want to try it yourself, the fact that the platters are spinning is a good sign that the problem is PROBABLY the circuit board. If you can find another drive of the same make/model and firmware revision, you can CAREFULLY swap the circuit board and may then be able to read the data from the drive.