(1)It shall be competent at any time before imprisonment has followed on a sentence for the court to alter or modify it; but no higher sentence than that originally pronounced shall be competent.
(2)The signature of the judge or clerk of court to any sentence shall be sufficient also to authenticate the findings on which such sentence proceeds.
(3)The power conferred by subsection (1) of this section to alter or modify a sentence shall be exercisable without requiring the attendance of the accused and, without prejudice to the generality of the power, shall include power, in the case where payment of a fine by instalments has been ordered, to reduce the amount, or allow further time for the payment, of any instalment (whether the time for payment thereof has or has not expired), or to order payment of the fine, so far as unpaid, by instalments of smaller amounts or at longer intervals than originally allowed.