I have the Dexter 4400# axle with 10" brakes and I can lock them up anytime I want.
The trailer is the 30RKS Cougar 8200 GVWR if that helps.
Given what you stated about the adjustment of the brakes I would make sure the voltage and amps were correct for each wheel. If that checks out I would pull the drums and do a visual inspection of each to see what is happening.
For your cold one I would suspect grease on the shoes since you had it on the face of the drum as well. very little really affects the braking.
Paul
