Certain retired teachers to be employed by retirement system as special school advisors and supervisors, when — actuarially unsound, effect of

1. Any retired teacher now receiving retirement benefits, who served five years or more as a teacher in the public schools of this state and who retired after June 30, 1957, and prior to January 1, 1971, under the provisions of this chapter, shall, upon application to the retirement system from which he is receiving retirement benefits be employed by that retirement system as a special school advisor and supervisor. Any person so employed shall perform such duties as the board of trustees of the retirement system of which he becomes an employee directs, and shall receive a salary of five dollars per month for each year of teaching service not to exceed seventy-five dollars per month, payable by the retirement system as part of its administrative costs, but the payment to the retired person for such services, together with the retirement benefits he receives under this chapter, shall not exceed one hundred fifty dollars per month. The employment provided for by this section shall in no way affect any person's eligibility for retirement benefits under this chapter. 2. Annually, immediately after the close of the fiscal year of each teacher retirement system, the actuary for the system shall determine if the payments made pursuant to the provisions of this section have impaired the actuarial soundness of the plan, and upon his certification that the soundness has been so impaired, the system shall bill each of the school districts which last employed each of these retired persons on a full-time basis for reimbursement of the amount paid to that person during the preceding fiscal year. The school districts shall forthwith accordingly reimburse the appropriate retirement system.