Signaling dissatisfaction with the National Assn. of Broadcast Employees and Technicians, 65 NBC and KNBC Channel 4 news writers, news producers and assignment editors are seeking to decertify the union's Local 53 as their bargaining representative. "A whole bunch of people--not just news writers--are not happy with NABET leadership and the way they've handled the (16-week-old) strike," said union member Bob Compton, a KNBC news producer. Local 53 spokesman Chuck Klein said a petition to decertify was filed last week by a disgruntled few. The National Labor Relations Board must now set a date to decide whether Local 53 can continue to represent the NBC strikers.