I could not find similar post here.

This is what I have: I got 5.25 drive that is in a quite good shape and when I first turned it on it did work , it did read but after few disks scratched badly and I cleaned it, it stopped working altogether. Namely, it will react to commands but it will report fail,abort. I found that the controller wont step the head and head selection flips 0,1,0,1,......... index sensor works, track0 works, all motors do work properly, when commanded appropriate signals are sent but no head movement. I can see read signal is present and I can see pulses.

Is there anyone here with expertise in fixing and diagnosing this device?