I'm don't think that my fwhs are locking, as I don't seem to have 4wd.
I freed the selectors that stick out of the front of the transfer box a couple of months ago, and thought I'd solved the 4wd problem that I had then.
The knob that changes between lock and free works as normal. On this knob is engraved selectro, and the fwhs are 9cm/3.5 inches deep.
If anybody can offer some advice as to stripping them or what to look for/check, I'd appreciate it.

try turning front prop with it in 4wd and 1 front wheel up if you cant turn it gear box in 4wd if you can its not,then jack and turn each wheel in turn with car in 4wd and they shouldnt spin if free wheel hub working and half shats diff etc okay