Section 35E. Any employee who is at least sixty-five years of age and has been out of the labor force for a period of at least two years and is eligible for old age benefits pursuant to the federal social security act or eligible for benefits from a public or private pension which is paid in part or entirely by an employer shall not be entitled to benefits under sections thirty-four or thirty-five unless such employee can establish that but for the injury, he or she would have remained active in the labor market. The presumption of non-entitlement to benefits created by this section shall not be overcome by the employee's uncorroborated testimony, or that corroborated only by any of his family members, that but for the injury, such employee would have remained active in the labor market. Claims for compensation, or complaint for modification, or discontinuance of benefits based on this section shall not be filed more often than once every twelve months.