Long story short, '97 disco, seized diff lock, etc etc.

Took the little guy apart, now in the process of taking the rust off the parts. Luckily it seems the diff lock works fine when applied manualy.

The problem I have is that I can't figure out what drives the diff lock. The shaft with the circular ring that holds the lever doesn't seem to move in or out, even with no more rust and well greased. I can't see a leverage point that would cause the diff lock to engage and disengage.

How does this bloody thing work?!!?