{HEAD ~ The knob} 80 has an annular portion 82 arranged for frictional engagement with the exterior surfaces of the rear wall 66 on each side of {TAIL ~ the slot} 76 
{ HEAD ~ The knob } 80 has an annular portion 82 arranged for frictional engagement with the exterior surfaces of the rear wall 66 on each side of { TAIL ~ the slot } 76
HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL OTH