Aluminum knurled knob
Purple Wire = Grey connector, pin 32
Black Wire = Grey connector, pin 50
Your DSP5 switch has a nut and two washers. The bottom smooth washer must remain on the bottom with the tab located in hole number five. If it falls out, turn the switch fully counter clockwise and place the washer back with the pin in hole five and make sure the switch moves exactly four clicks clockwise. If not, turn the switch back fully counterclockwise, move the pin and try again.