PUBLIC LAWS-CH. 120 -JUNE 23, 1947 Excessive or dis. criminatory fees. Payment by em- ployer for services not performed. "To bargain collec- tively." employees if another labor organization has been certified as the representative of such employees under the provisions of section 9; (D) forcing or requiring any employer to assign particular work to employees in a particular labor organization or in a particular trade, craft, or class rather than to employees in another labor organization or in another trade, craft, or class unless such employer is failing to conform to an order or certification of the Board determining the bargaining representative for employees performing such work: Provided, That nothing contained in this subsection (b) shall be construed to make unlawful a refusal by any person to enter upon the premises of any employer (other than his own employer), if the employees of such employer are engaged in a strike ratified or approved by a representative of such employees whom such employer is required to recognize under this Act; "(5) to require of employees covered by an agreement author- ized under subsection (a) (3) the payment, as a condition preced- ent to becoming a member of such organization, of a fee in an amount which the Board finds excessive or discriminatory under all the circumstances. In making such a finding, the Board shall consider, among other relevant factors, the practices and customs of labor organizations in the particular industry, and the wages currently paid to the employees affected; and "(6) to cause or attempt to cause an employer to pay or deliver or agree to pay or deliver any money or other thing of value, in the nature of an exaction, for services which are not performed or not to be performed. "(c) The expressing of any views, argument, or opinion, or the dissemination thereof, whether in written, printed, graphic, or visual form, shall not constitute or be evidence of an unfair labor practice under any of the provisions of this Act, if such expression contains no threat of reprisal or force or promise of benefit. "(d) For the purposes of this section, to bargain collectively is the performance of the mutual obligation of the employer and the repre- sentative of the employees to meet at reasonable times and confer in good faith with respect to wages, hours, and other terms and conditions of employment, or the negotiation of an agreement, or any question arising thereunder, and the execution of a written contract incorpo- rating any agreement reached if requested by either party, but such obligation does not compel either party to agree to a proposal or require the making of a concession: Provided,That where there is in effect a collective-bargaining contract covering employees in an industry affecting commerce, the duty to bargain collectively shall also mean that no party to such contract shall terminate or modify such contract, unless the party desiring such termination or modification- " (1) serves a written notice upon the other party to the contract of the proposed termination or modification sixty days prior to the expiration date thereof, or in the event such contract contains no expiration date, sixty days prior to the time it is proposed to make such termination or modification; "(2) offers to meet and confer with the other party for the purpose of negotiating a new contract or a contract containing the proposed modifications; "(3) notifies the Federal Mediation and Conciliation Service within thirty days after such notice of the existence of a dispute, and simultaneously therewith notifies any State or Territorial agency established to mediate and conciliate disputes within the State or Territory where the dispute occurred, provided no agree- ment has been reached by that time; and 142 [61 STAT.