The technician not fully aware of the type of model trimmer that I had which caused some confusion. He insisted that there was *** in the post on top of the shaft not realizing that only applied to the newer models which I did not have. After the confusion was cleared up he was then able to direct me in the correct course of action which was to hold the upper shaft post with a monkey wrench and then spin the upper housing counter clockwise. User's recommendation: Make sure the technician has your exact make and model, not just the description of the tool.