said first mentioned guiding means including means for slidably confining the front portions of {HEAD ~ the respective push buttons} against {TAIL ~ movement} away from said port member to assist in maintaining compression of said valve members and thereby maintaining sealing pressure between said valve members and said port member 
said first mentioned guiding means including means for slidably confining the front portions of { HEAD ~ the respective push buttons } against { TAIL ~ movement } away from said port member to assist in maintaining compression of said valve members and thereby maintaining sealing pressure between said valve members and said port member
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD REL 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