Upon application of a member in service or of his or her employer or of his or her legal guardian or of the legal representative of a deceased member who was eligible to apply for a temporary disability allowance based on the final illness a member shall be granted a temporary disability allowance by the department if the medical director, after a medical examination of the member, certifies that the member is mentally or physically incapacitated for the further performance of duty. Any member receiving a temporary disability allowance on July 1, 1964 or who qualifies for a temporary disability allowance effective on or after July 1, 1964 shall receive a temporary disability allowance of one hundred eighty dollars per month for a period not to exceed two years, but no payments shall be made for a disability period of less than sixty days: PROVIDED, That a member who is not employed full time in Washington public school service for consecutive fiscal years shall have been employed for at least fifty consecutive days during the fiscal year in which he or she returns to full time Washington public school service before he or she may qualify for temporary disability benefits: PROVIDED FURTHER, That no temporary disability benefits shall be paid on the basis of an application received more than four calendar years after a member became eligible to apply for such benefits.