Section 1405. When court may dispense with testimony of witness 1

The death, absence from the state or incompetency of an attesting
  witness required to be examined as prescribed in this or  the  preceding
  section  or the fact that the witness cannot with due diligence be found
  within the state or cannot be examined as an attesting witness by reason
  of his physical or mental condition may be shown by affidavit or by  any
  competent  evidence and when so shown to its satisfaction, the court may
  by the decree on probate or by order either in writing or entered in the
  minutes dispense with the testimony of such attesting  witness.    Where
  the  testimony  of  an  attesting  witness  has  been  dispensed with as
  provided in this section and 1 attesting witness has been  examined  the
  will  may  be  admitted  to  probate upon the testimony of the attesting
  witness who has been examined without further or additional proof.
    2.  Where an attesting witness is absent from  the  state  and  it  is
  shown  that  his testimony can be obtained with reasonable diligence the
  court may and shall upon the demand of any party require  his  testimony
  be taken by commission.
    3.    Where  an  attesting  witness  has  forgotten  the occurrence or
  testifies against the execution  of  the  will  and  at  least  1  other
  attesting  witness has been examined the will may be admitted to probate
  upon the testimony of the other witness  or  witnesses  and  such  other
  facts as would be sufficient to prove the will.
    4.    If  all  of  the  attesting witnesses are dead or incompetent or
  unable to testify by reason of  physical  or  mental  condition  or  are
  absent  from  the  state  and their testimony has been dispensed with as
  provided in this section  the  will  may  nevertheless  be  admitted  to
  probate  upon  proof  of the handwriting of the testator and of at least
  one of the  attesting  witnesses  and  such  other  facts  as  would  be
  sufficient to prove the will.