Based on talks with a guy who was part of a plant tour at the manufacturing facility in Alabama, the twenty somethings at the end of the production line did not have files and were not doing anything but screwing parts together. They also did not have chairs to sit on! That is apparently the production philosophy, no hand fitting at the end of the production line. So if the assemblers had noticed anything off, assuming they understood the problem, they could not fix it, and were not expected to fix it. And, from what I have heard, the weapons are not targeted, they are function tested. As long as it goes bang, it does not matter if the bullet is landing 20 feet away from the point of aim. From what I understood, the New Haven Marlins were assembled by handfitters who understood alignment issues. My New Haven Marlins are correctly assembled, except the M336 has a huge chamber. I talked with New Haven Customer service at the turn of the century, they were building rifles for brush hunters, not target shooters, or for that fact, reloaders.
I am not surprised you received subsequent defective rifles. I don't know if Remington is actually fixing rifles, or just shipping new replacements out of a pile of inventory. That would explain canted sights on your replacement rifles, the same problem, from a batch of rifles, that had not shipped yet. They might not have a repair facility, or real gunsmiths in the plant.