The agreement shall include each coverage group as to which formal request for inclusion is made by the legislative or governing body of the employing public agency pursuant to ORS § 237.440, prior to the effective date of the agreement, or any modification thereof. However, the board shall not be required to include in any agreement or modification any public agency which is not entitled by law to share in any apportionment of state revenue or funds and has at any time within the 10 years next preceding the date of its application been insolvent or failed to pay when due, the principal or interest of its bonds, warrants or other obligations. [Amended by 1953 c.192 § 3(1)]