Notwithstanding the provisions of sections 5-176, 5-177, 5-177a, 5-181, 5-184, 5-187a, 5-189, 5-190, 5-190a, 5-192a, subsection (b) of § 5-180 and subsections (b) and (d) of § 5-182, no member who is eligible for credit for such service but who has not yet purchased such credit shall receive credit for such service on or after the first of the month following three months after June 28, 1985. Prior to that date, any employee eligible to receive such credit and who desires to receive such credit shall so notify the Retirement Commission. If such employee is financially unable to complete the payment of the required contributions for such credit prior to such date, the Retirement Commission and the employee may enter into a contract for payment of such amount in not more than fifty-two equal biweekly installments. Such installments shall include interest at five per cent per year, and such service credit shall not be granted unless payment of installments is completed. The Retirement Commission shall liberally construe the provisions of sections 5-176, 5-177, 5-177a, 5-181, 5-184, 5-187a, 5-189, 5-190, 5-190a, 5-192a, subsection (b) of § 5-180 and subsections (b) and (d) of § 5-182 and this section in determining whether an employee is eligible to purchase such credit.