I just acquired an Aero Longshoreman in excellent condition, except for its quilt-rayon lining along the bottom interior. Its horsehide is thick enough to be body armor. . . which brings me to its brass zipper. The zipper is in good condition, but either it is sticking or its surrounding horsehide is so thick that zipper action is sluggish. My first thought after verifying everything is clean was to apply a small quantity of Break-Free CLP® to zipper's fastener and teeth, then cycle the fastener several times to be sure lubricant would be thoroughly spread. My next thought was: Ask for a solution from people who have substantial experience with jackets of this type. What need be done to render the zipper easier to use?