There are no missing Z film frames. What you see is what happened. If you want to continue to believe there are 67% of the frames missing, go over to another forum called the (UN)education Forum. Do a search there for a thread called SWAN SONG MATH RULES and dive into the muck over there. You'll find plenty of like-minded souls there who think the same thing about the film. Good luck.
It appears to me that Robin Unger's gallery for Zapruder doesnt have any of the 6 missing frames, & it also doesnt have non-damaged frames ie without splices. But that link to Costella does have.
And it appears to me that there are a few poor quality youtubes with the missing frames etc, but Costella is the only good quality movie.
I had a quick look at that site/link & i couldnt fathom their point(s), whats their beef, do they reckon that Zapruder has been censored or changed, i dont.
I dont believe in any conspiracies except for the Hickey cover-up afterwards.
Which includes secretting or destruction of footages by Oliver & Arnold (koz they show Hickey).
And The 6th Floor Museum wont allow public access to the superior 2019 copy of the Bronson frames which are better than the 2017 copy & i am sure will show more clearly that Hickey did it.
And i am suspicious re the missing frames in the Towner footage.