A press is mounted to {HEAD ~ the base} to selectively press {TAIL ~ the press block} against the gasket and hold it in position 
to selectively press
A press is mounted to { HEAD ~ the base } to selectively press { TAIL ~ the press block } against the gasket and hold it in position
OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD REL REL REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH