The gasket 18 is then positioned on the active surface 16 of the substrate so that {HEAD ~ the central opening} 19 in the gasket is fully within {TAIL ~ the window} opening 21 of the base at a proper position, and the press block 13 is then positioned over the gasket 18 so that the engagement surface 20 properly seats against the gasket 18 
is fully within
The gasket 18 is then positioned on the active surface 16 of the substrate so that { HEAD ~ the central opening } 19 in the gasket is fully within { TAIL ~ the window } opening 21 of the base at a proper position , and the press block 13 is then positioned over the gasket 18 so that the engagement surface 20 properly seats against the gasket 18
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH REL REL REL 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