I have a pair of Look 99's with the brake up by the toe. The adjuster screw turns but it is very tight and I have a feeling that it is crossed threaded. I got them used and that is the way they came. I am almost afraid to back it off or all the way out because I may not be able to get it back together. Could it be tapped or thread back to the original thread and does any know what thread is used on the adjuster screw?
could be cross threaded also could be rust or contaiminaton. I typically use a large putty knife multi tool called a 5-in-one, to open these bindings they can be VERY stiff after years in the same location. you could also try soaking with WD40 or some other light weight oil it is a bit of a labyrinth to get to the threads but just a little bit might help.