You believe there is solid evidence the Zapruder film was altered?
Familiarise yourself with Roland Zavada and his report on the authentification of the Zapruder film. You can then put any silly notions of alteration behind you.
I agree. The experts (it wasn't just Zavada although he was, from what I've read, the most knowledgeable person about the film/camera) who studied the film said they saw no alteration. What are we to do with this pretty important conclusion? Just dismiss it? Zavada was a serious man, an expert on the camera and the film.
As to the doctor's accounts on the head wound:
Let's ask the question: Why would those *emergency* room doctors (remember: not all of them said back of the head; some said side; *see below) at Parkland in a, as they explained, brief hurried setting, be correct about the location of the wound but the autopsy doctors at Bethesda who examined the president for four hours and closely studied the head wrong? What makes the first group right and the second group wrong?
To put it differently: You have one group of doctors whose job it was to save the patient and NOT study the wounds and another group of doctors whose job it was TO study the wounds and not save the patient (since he was, of course, dead). So we have two completely different situations. Which one is more likely to "get it right"? Why would anyone rely on the ER doctors over the autopsy doctors? What makes that conclusion correct?
Moreover, the doctors at Bethesda have films, x-rays and photos - physical evidence - that supports their explanation. The Parkland doctors have none of that.
It seems to me that if you weigh the Parkland doctors accounts versus the Bethesda doctors accounts PLUS the photos and x-rays and films that it's not close who is right. We can add the accounts of the Connallys and Kellerman who said they were hit/sprayed with blood and brain matter. How could a blowout in the back of JFK's head deposit matter to the front of him? It's impossible. The motorcycle officers - Hargis - said he "rode" through it as it came down. He also said he was watching JFK and saw no exit wound out of the back of the head; only a "splash" out the side. So why didn't he see this rear blowout?
Add to it Zavada's analysis and the timeline and chain of possession of the film and I don't see how one can conclude it was altered.
*Dr. Charles Baxter, one of the attending physicians at Parkland: After JFK was pronounced dead "We had an opportunity to look at his head wound then and saw that the damage was beyond hope, that is, in a word-- literally the right side of his head had been blown off." Right side of the head NOT the back. Yes, other doctors said back of the head; why are they right and Baxter wrong?
Source/link for the above from Baxter:
https://www.jfk-assassination.net/russ/testimony/baxter.htmJFK's skull x-ray on the right. No back of the head/rear exit. It's intact. Just as the Bethesda doctors said and the Zapruder film shows.