Flip-flop
by Kegler

Eight answers must be modified before entry into the grid, as described by the five-word phrase     
in the unclued top and bottom rows (one of the eight is a rather loose interpretation of the phrase).

Across 1 See instructions 7 Serve beginning of trial period 8 Element twisted in coils 10 Moves the camera back; host upset with picture 13 Unusually tame pair of horses 14 Sparkling bay surrounds river's mouth 16 Bill with Franklin making a comeback 17 Live in backward time 18 Drums of paint I'm stirring 20 I wondered about comforter 23 Family member embraces head of pediatric nurses 24 Cozily left gun inside; shrewd 25 Hoax, for example, initially perpetrated amid recess (hyph) 29 Kind one extremely lovesick 31 Split a pipe showing source of water 32 Second printing displayed by bookstore is suede 33 See instructions

Down 1 Final value: ten, adjusted 2 Reportedly is aware of feature 3 Neat! Erupting volcano 4 Eleven people initially ducked around tip of object, sword-shaped 5 Electric eel swallowing food 6 Shed energy upon compression, finally, like magma 9 Nearly dent in central molding 11 Young man is a star, we hear 12 Depressingly slim lady's drunk 14 Supporter and I will start to examine dotty system? 15 Small, quiet cry 19 Lists me and, essentially, our group 21 Trio from Russia arranged homespun fabric 22 Undisturbed tartan bearing edge of crease 23 Avoid article of clothing 26 Cut fuel handling, at first 27 Attitude thus rejected in gym class 28 Fight is ultimately average 30 Young cat's set of tools

Solution