Ok... I used to run a bike workshop.
Remove the plastic cap from bar.
Loosen the rear fasteners then the front. Take out the rear fasteners and then the front. Remove the top cap. Lift the bar gently from the support.
Lift off one block, rotate 180 deg. and replace. Do this with the other block.
Replace bar and caps, lining up the punchmark on bar with the edge of the block as the front fasteners are gently tightened. Then replace the rear fasteners. Torque the front fasteners, then the rear.
Replace plastic cap.
Don't blame me if you crock it on the first corner.
I'm off to service my Saturn IV now.