Just looked closely at the parts catalogue and Drags' offering. There appear to be two variants of the hub brake lever, one with a fixed lever and loose cam, or fixed cam and loose lever! Solving the problem of getting something big (the cam) through a small hole....
Either way in this case the lever and its relationship to the cam looks to be fixed, and as CJ suggests, if full available adjustment does not restore the lever to a lower starting point, it's new shoe time. The lower the better, within reason, as the hub lever should end up just before 90 degrees to the cable with the brake applied good and hard.
Swarfy.
Additional. Part 42 5573 pictured on Drags' today does not exactly inspire confidence, but could explain poor brake performance...only joking, but makes you think. If the hub is the type with loose cam, this is available, and replacement can also improve matters, fitment looks to be a straighforward swap.