Section 51 of the Principal Act is amended as follows:(a) by omitting from subsection (1) "Board" twice occurring and substituting "Tribunal" ;(b) by omitting from subsection (2) "Board" and substituting "Tribunal" ;(c) by omitting from subsection (3) "Board" and substituting "Tribunal" ;(d) by omitting from subsection (4) "Board" and substituting "Tribunal" ;(e) by omitting from subsection (5)(a) "Board" and substituting "Tribunal" ;(f) by omitting from subsection (6) "Board" and substituting "Tribunal" .