No. 91-3729. Submitted November 9, 1992. Decided March 5, 1993. Harry W. Zanville, Waterloo, IA, argued, for petitioner. Vincent Falvo, Washington, DC, argued, for respondent. Appeal from the National Labor Relations Board. Before RICHARD S. ARNOLD, Chief Judge, LAY, Senior Circuit Judge, and LOKEN, Circuit Judge. LOKEN, Circuit Judge. Following a lengthy evidentiary hearing, the National Labor Relations Board concluded that respondent DBM, Inc., violated §§ 8(a)(1) and 8(a)(3) of the National Labor