The shaft 26 includes {TAIL ~ an angularly offset portion} or eccentric 28 which is disposed within {HEAD ~ the chamber} 16 
The shaft 26 includes { TAIL ~ an angularly offset portion } or eccentric 28 which is disposed within { HEAD ~ the chamber } 16
OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD OTH