I have a 1974 580b backhoe/loader the differentional lock pedal moves very little. I looked at one and the arm that the pedal hooks to is at the 10 oclock position and mine is in the 12 oclock position and i can move it by hand very little about to the 11 oclock position is there something i can do or check or is this better off left alone dont want to spend alot on it.
There is not much to it, under that little cover is a coupler with two small guides, a fork that moves the coupler guides. It slides that coupler on the diff lock shaft to engage the side gear splines and locks the rear wheels together. There is a roll pin that holds the fork to the shaft and a small spring that pushes the coupler fork to the release unless the pedal is pushed down to engage. At the end where the linkage hooks, that linkage has a spring in it. When force is pushed down on the pedal, that linkage moves and holds tension until the coupler inside that cover splines line up and allow it to slide and lockup. Machine has to be moving for it to line up and en gauge. If all parts are there you may need a roll pin and some wd40 to free it up, kind of a pain but worth it in the long run.
thanks when i get a chance i'll dig into it and see what i can find