Abstract: A brush holder assembly that cannot be assembled incorrectly includes a brush inserted into a brush holder, a block attached to the top of the brush, a spring engaging the block that applies radial pressure to the block and brush, and a hook pin that holds the spring onto the block. The block includes a semicircular indentation that cradles a coiled portion of the spring and includes a slotted hole for receiving a portion of the hook pin as the block is glued to the top of the brush. The hook pin is a loop terminating at a first end that is a straight pin and terminating at a second end that is a hook-shaped loop in which the straight pin end is inserted. Alternatively, a U-shaped spool assembly can be used to engage the coiled portion of the spring to lock it in the indentation in the block.