Transfer box linkage

I have read numerous threads on this issue but can't find what im looking for. Diff lock seized. Told has been for 8 years. Removed and freed. low high range now ok. Lever moves rod about 1/2 inch sideways. Diff lock working easily via socket. Put diff lock linkage back on, but when i move the lever to side, it just rotates the u-shaped connecting rod from bottom of linkage to cam, and does not operate cam.
Struggled for access to linkage no skin left on back of my hand.
Is there supposed to be something to stop the rod turning?
Am i best dropping front prop to gain better access?

has the lever pivot still got the 2 plastic bushes , linkage needs to have little play and adjusted correctly by pivot to operate

yes still has bushes. the linkage seems to operate ok, it;s the u shaped connecting rod that instead of pushing against the diff lock cam, it just swivels around it