Question: For more than thirty years without challenge by the union, the Brod & McClung-Pace Co.'s bargaining unit employees performed warranty work at customers' facilities. Then the international union altered its constitution to forbid its members to do such warranty work. Pursuant to this constitutional change, the local union, which was subject to the international's constitution, sought a midterm modification of its collective bargaining agreement with the company to eliminate the warranty work. When the firm refused, the union sought to achieve a unilateral change by threatening its members with court-collectible fines if they continued to perform the work. Did the union violate the NLRA? If so, how? See Sheet Metal Workers Int'l. Ass'n., Local 16 [270 NLRB 116 (1984)].