In the event of default in the payment of principal [of], or interest on, an investment made, the investment officer is authorized to institute proper proceedings to collect matured interest and principal; the investment officer may, after consultation with the investment council, accept for exchange purposes refunding bonds or other evidences of indebtedness at interest rates to be agreed upon with the obligor. The investment officer, after consultation with the council, is authorized to adjust past-due interest or principal in default.