Speed control knob removal?

The speed control knob consists of 5 parts excluding the shaft: The external plastic round dial, a small plastic cover in the middle of this, an internal nylon insert that has a groove on one side that is not concentric, a spring between the two, and the small circlip that holds the whole lot on the machine. Care should be taken when fitting it. The nylon and plastic bits are keyed and only go one way. There is a small metal bar which raises and lowers the speed control PC board. The bar must fit into the groove on the nylon insert so that the dial raises or lowers the board

mal
February 2011