The hall probe was set 0.05 inches or 1.27 +/- 0.2 mm above the block.

The hall probe element is located somewhere at in the middle of the probe stem which is 1.524 mm thick.  

The location of 

If  the hall probe element was in the middle then 1.27 + 0.762 = 2.032 +/- .2 mm from the