TPR57C: The pawl is spring loaded I believe. Are you manually pushing on pawl so that is catches in tooth or are you manually releasing it to release brake? Seems like it's the spring on trigger/pawl. The unit comes out to bench very easily. One cotter pin, one clevis pin, 3 bolts.
There is also a linkage return spring, I don't think that is what you are having trouble with?

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