The theory that Chaney was removed is based on his testimony that he rode forward past the limo right after the head shot, but the Nix and Z films show he did not ride forward. Yet 3 of the 4 people in Curry's car said he did ride up to them and that he told them the president has been hit.
If the limo stop was removed from the Z film it would leave no time and space for Chaney to ride forward AHEAD of the limo and speak to Curry. So Chaney's ride forward would have to be removed too.
And that is the problem that that the Alterationists need to explain.
If a such large number of frames were supposedly removed from the Zapruder film
the Limo Stop, Chaney's ride forward to the underpass.To make the two films sync, all of the corresponding frames in Nix would have to be removed as well
What we see in Nix tells a different story
We see the heashot, immediately after it the Limo slows to a crawl, as the Limo slows to almost a stop, Channey and Jackson hit the brakes and the queen mary passes them.
At this point Chaney is left behind as greer guns the Limo and speeds off towards the underpass,
at which point we see a large gap open up between the limo and the rest of the motorcade, who are still situated in the area next to the grassy knoll steps.
In Altgens 7 we see the lead car and we see the limo heading for the underpass ( there is no one else seen in Altgens 7 )
In Nix we see the heashot, immediately after the headshot the Limo slows to a crawl, as the Limo slows to almost a stop, Channey and Jackson hit the brakes and the queen mary passes them.