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