An individual shall not receive a pension under this subchapter for any month during which the individual is an employee, as defined in § 8351(5) of this title or § 5501 of Title 29, unless the individual is:
(1) An official elected by popular vote at a regular or special election; or
(2) An official appointed by the Governor; or
(3) A registration or election official, or a juror; or
(4) Receiving an ordinary service, disability or survivor’s pension.
The employment, except employment as an elected official, may not be used for further retirement benefits.