{HEAD ~ The invention} 7, wherein {TAIL ~ the first detent means} comprises an annular array of detent teeth, a first segment of the array comprising a first number of detent positions and a second segment of the array comprising a second number of detent positions; and 
wherein
{ HEAD ~ The invention } 7 , wherein { TAIL ~ the first detent means } comprises an annular array of detent teeth , a first segment of the array comprising a first number of detent positions and a second segment of the array comprising a second number of detent positions ; and
HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH