brake adjuster on front wheels on a P3.

I need some advice on keeping the adjuster in place. when i adjust the front brakes, then go for a run the adjuster on the r/hand side reverts back to where it was before adjusting. it appears that the adjuster is part of the backing plate i doubt if there would be any of these in reasonable condition about the ridges, may be the notched edges on the adjuster are badly worn. any suggestions would be greatly appreciated best regards Derrick.Smith.