said first mentioned guiding means including means for slidably confining {HEAD ~ the front portions} of the respective push buttons against movement away from said port member to assist in maintaining {TAIL ~ 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 { HEAD ~ the front portions } of the respective push buttons against movement away from said port member to assist in maintaining { TAIL ~ 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 HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH