All the intermediate positions between these two end positions blocking the orifices 7 allow {HEAD ~ the loss} of {TAIL ~ head} to be adjusted partially as required 
of
All the intermediate positions between these two end positions blocking the orifices 7 allow { HEAD ~ the loss } of { TAIL ~ head } to be adjusted partially as required
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH