Riverside police officials said "everything was peaceful" on the fourth day of a machinists' union strike at Rohr Industries Inc., as about 2,000 strikers entered the plant to receive their paychecks. On Wednesday, however, six members of the International Assn. of Machinists and Aerospace Workers, Local 964, were arrested on suspicion of driving under the influence and violating a court order limiting pickets. On Tuesday, 14 people were arrested when violence erupted as management officials tried to enter a gate during a shift change, authorities said. No bargaining talks were scheduled.