maybe someone else has previousely posted this but im not sure.
i have a clx-22 old type clips,the top and second sections both slip and drives me mad.
to repair i have removed srew from clip and fitted a small washer over threaded stem,then re fitted screw,this has solved the problem,no more slipping.,two washers were required for second section.
basically what the washer does is lengthen the threaded screw giving you more thread to tighten clip.
hope this of help to others