Open the dishwasher door. Pull the lower rack out as far as it will go.
Lift the front end of the lower rack up. Pull the rack toward you to completely remove it from the MDB5600AWB cabinet.
Insert the tip of the flat-blade screwdriver into the locking tabs on the upper spinning arm retainer. The tabs are located near the tip of the spray arm. Rotate the screwdriver to spread the locking tabs.
Slide the upper spinning arm out of the wash arm retainer.