techknight said:

Careful with this. You can actually throw off the cylinder alignment (head to head) and it wont read anything anymore. 

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You need to be cautious when bending the top spring, it needs to be done lightly.  I found the safest method was to bend lightly then test and repeat if more tension is required.  Event with the screw driver in place the effect on the spring is very minimal because the top head still doesn't have much room to travel down before it touches the bottom head.  It's quite a safe procedure as long as you're careful.  With the second drive that I fixed the top head had been bent up due to cleaning, it was a good 5mm above the disk.  This procedure fixed it.