If at any time the amounts derived from the different sources provided in this chapter are not sufficient to enable the board to pay in full each person determined to be entitled to annuities or benefits under this chapter, then each beneficiary shall receive a prorated percentage of the monthly benefits otherwise payable until the fund is sufficiently replenished to warrant the resumption thereafter of full payments of such annuities or benefits to each beneficiary. In no event shall the board, or any member of the board, be liable to any beneficiary or the representatives of any beneficiary for any deficiencies in payments made under this Code section.