21 OF 459 CAPTIVES WON BACK BY REDS IN VIOLENT SESSION; Only 5% of North Korean Group Accede to Foe's Cajoling and Accept Repatriation
459 NKs processed by Communist explainers; 21 ask repatriation; Allied observers surprised that Communists ask further sessions in view of poor results; most NKs have to be restrained by guards from assaulting explainers