K.S.A. 58-2309 shall be construed so as to apply to mortgages heretofore paid, but not discharged of record: Provided, That if the residence of the holder of such mortgage can be ascertained, no action shall be brought until demand is made in accordance with said section; but such demand need not be in writing, and will be excused if the residence of the holder of such mortgage cannot, with due diligence, be ascertained.
K.S.A. 58-2310