Last year I bought an IOD 1889, with a folding guard. It's handle had almost completely rotted away, and the Pommel cap, knuckle bow, and very end piece that threads onto the tang do not line up correctly. I'll attach some pictures of the way they sit in different positions.
[ Linked Image ]
With the knuckle bow "keyed" into the pommel cap, you can see there's a large gap in between the cap and the threaded end piece.
[ Linked Image ]
With the pommel cap pressed against the end piece instead, there is now a gap in the slot for the knuckle bow and it does not fit properly.
The tang and all other hilt components are all stamped with the number "13', as I understand it this is to mean they all belong in the same set? Any help as to why it does this, like a bent tang or knuckle bow would be appreciated.

I suspect that when the wood grip core was in place, it held the knuckle bow at the proper spacing against the end-cap. This would have helped keep things from rattling. When the grip core rotted away and fell off, the knuckle bow sprang down a wee bit over time with wear. The grip core would also have helped keep the end-cap assembly tight together as well, when you include the leather or rayskin wrap that would almost certainly have been there as well.

That would make sense, it does look a little like the knuckle bow has a crimp in it.