IWS focusing help/advice

[Elphiel]

Hi,
here is a picture of how the part with the internal focus lens schould look like if you get it out. On the top sits the lens itself. You can see a little plate with the slit screwed onto its side. If you already removed the front lens, you can also simply pull out that shown tube. Either that plate is missing/loose OR the pin inside the thumbscrew itself is missing/broken/loose.

Also little correction to Peter. The screw is not for adjusting eye errors/dioptrin, as that would be done in the eye piece lens. Because of the intensifier tubes viewscreen, the eye correction can only be applied for the focus from eye to viewscreen plate on the intensifier tube. The discussed thumpscrew is the adjustment for focus from close range to infinity of the target.

:edit: I think the little plate is still where it should be, but the two screws that fix it to the focus lens assembly tube are missing. So in your case, the thumbscrew only moved the little plate, but the focus lens assembly stayed in its position.