Across:
   1. Some Maori gaming the system, making improvements only on paper (7)
   5. Liberate, as barber does? (6)
   9. Notice lust quite developed in such individuals (6)
  10. Second auditor, by whom many get fleeced? (7)
  11. Thus this is how I steer, or is where to! (9)
  12. Where the sun rises on naked beasts (4)
  13. Stuffing only four out of nine into public transport (4)
  15. Killer chemical and panic it set off (10)
  17. see 27
  19. Almost wipe out whole chunks of history (4)
  20,3dn. Keeper and saviour follows a mother with girl not close to father (4 9)
  22. see 7 down
  25. City in Colorado (with Utah to the west) more prominent (7)
  26. see 15 down
  27,17. Writer and saviour finally appearing (after foody mess) with party votes rigged by media company (6 10)
  28. Heard team song's offensiveness (7)
Down:
   2. It may use a varactor (a diode) in part (5)
   3. see 20 across
   4. Timeless Mr Scrooge! (5)
   5. United with Monica on court... cunning, but to no avail (9)
   6. Singer and saviour on ecstasy (5)
   7,22ac. Actress and saviour in a computer program has member consumed (9 9)
   8. Help player of four string guitar when missing its fifth string? (6)
  14. Little avocado I smashed badly, which is in a way unnecessary (9)
  15,26ac. Reformer and saviour (second), leader accepting unknown and new label, oddly cheeky (9 6)
  16. Terribly bad beef followed PR put together earlier (9)
  18. Awesome bird fleeing American sporting event (6)
  21. Hill surrounded by American bases? (5)
  23. Old guy not initially wise when he joins metal bands perhaps (5)
  24. Seventieth should involve one! (5)