It looks as if everyone is stumped by this one. I am too, but wonder if a wobbling wheel bearing, loose drum, warped or thin drum might make it possible for the shoe to overextend briefly, enough to click the adjuster one notch too tight. It seems as if there must be something that is allowing the shoe with the adjuster to pull out further than it normally would. Another possibility might be some kind of wear or misalignment of the bottom end of the leading shoe, or whichever shoe it is that pulls the adjuster cable. I'm picturing some kind of movement that allows the shoe to move too far around, pulling the cable too far in the process.
I'm assuming the arrangement is more or less similar to the typical American drum setup such as we have on XJ's, in which the upper end of one shoe, pushed by the slave cylinder, pulls on a cable which in turn clicks the adjuster, which pushes the lower ends of both shoes outward, thus, we hope, decreasing the overall travel at the top end. That whole design seems pretty mickey-mouse, and I've always wondered why they haven't managed to improve it.
