CMP brake question

[Grant Bowker]

Is it possible that the spring for the offending adjuster has either partially or fully cracked? This would cause loss of tension and also create blunt ends at the crack site instead of the ground flat ends of the spring. Possibly leading both to reduced tension and angled application of pressure. I've only seen one such cracked spring (that I recognized, maybe there were others) and it wasn't very obvious.
Just curious, do you notice any difference in force to rotate the two directions on that spring and compared to the other spring on the same wheel? You might have to take out the brake shoes to get enough rotation to notice and remove the effects of all parts other than the specific spring but you are probably getting close to doing that as you investigate.....