(A) That applicants for such service qualifying under the provisions of the first paragraph hereof, shall present to the board of trustees of said state retirement system, a certified statement of such employment service from the responsible head of the state department, or departments, in which such employment accrued, or of the state, county, city or special school districts, educational system, or county from which credit for service is claimed, said statement to be in such form and content as required by said board of trustees; provided, that in the absence of original records pertaining to such employment service, the board of trustees may accept, in lieu of such certified statement, a sworn affidavit from a person or persons having actual knowledge of such employment service, said affidavit to be in such form and content as required by said board of trustees.
(B) That such applicant shall pay into the state treasury, for the use and benefit of said board of trustees, such sum or sums as would have been paid had this section been in effect and had such applicant been a member of the said state retirement system at the time of employment for which credit is claimed, provided that any member claiming prior service shall pay in cash with interest thereon at six per cent (6%) per annum such back contributions as shall be necessary to effect such claim.