I assume that when coins are placed in slabs, they're done manually. As such, no doubt that would be minute human visual error in alignment. By that, I mean that the axes of the coins do not coincide with those of the holder. See attached photos for what I mean. I'm sure there are worse examples out there. I was wondering if there is a maximum misalignment tolerance. 45 degress? I suppose they would be more careful with rarer and valuable coins than the mass marketed ones like these. Still, this can be avoided by an app that can quickly and effectively spot such misalignments in the QA/QC process.
May I ask how? I happen to have one like that. I tried tapping it on the opposing side but didn’t do any good.
Larry's comment did say "sometimes". Either tap harder or accept that this method of straightening won't work.
You have the right idea but it will not always work. I have known folks that cracked the slab trying.
As far as I know, the tapping method only works with 'rattler' (older) slabs. The newer slabs (with their plastic tongs) won't allow any movement........
Hold the slab vertically and bring it down in an arc, striking the bottom corner on something hard. It might take a while, but it usually works for me.
The prongs will allow movement. You just have to be a little more forceful with the tapping (but not too forceful... you don't want to crack it....)
You can try tapping the holder to move the coin. All you can do is try. If it doesn't work, it's probably going to stay that way, or you may even rotate it more the wrong way, like I have once. I've seen some world coins inserted completely upside-down in that NGC rubber core because the person doing it obviously didn't know the orientation of the non-latin alphabetic writing on the coin! However far the coin is rotated in a holder, it makes for a bad presentation, that's for sure.
If it's really bad I'd try to send it in for correction as a mechanical error. For minor rotations though there's not much you can do. You can send instructions with your submissions as to how to orient the coin. Sometimes they just get it wrong.