I've got only two small, very troublesome clues left - would appreciate some help.
4 D. Sound of any power plant (3) ?e?
16 A. Had to tear out weed (4) ??i?
('drip'/weed is an option, with 'rip' being 'tear out', but I don't see how it fits the rest of the clue.
The last letter in 4 D is also the last letter of 16 Across.