Ok, I may have been wrong about the location and style of the adjuster, but I stick by my original assertion that there is one. Just been a long time since I worked on a PL411... I'm trying (and failing) to find a diagram or picture of the brakes online, but my next memory tells me there is an offset peg that goes through a hole in the shoe that is used to move it closer to the drum. Can someone confirm if I am correct?