Application for review of half-monthly payment under Section 6 may be made without being accompanied by a medical certificate.
(a) by the employer, on the ground that since the right to compensation was determined, the workmen’s wages have increased;
(b) by the workman, on the ground that since the right to compensation was determined, his wages have diminished;
(c) by the workman, on the ground that the employer, having commenced to pay compensation, has ceased to pay the same, notwithstanding the fact that there has been no change in the workmen’s condition such as to warrant such cessation;
(d) either by the employer or by the workmen, on the ground that the determination of the rate of compensation for the time being in force was obtained by fraud or undue influence or other improper means;
(e) either by the employer or by the workman on the ground that in the determination of compensation there is a mistake or error apparent on the face of the record.