O ring 109 seals against {HEAD ~ fluid leakage} between {TAIL ~ retainer plate} 104 and rear cover 89 
between
O ring 109 seals against { HEAD ~ fluid leakage } between { TAIL ~ retainer plate } 104 and rear cover 89
OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH