Trailer Surge Brakes

[Galaxy24]

Looking for some assistance with my surge brakes.

The problem is that the first brake caliber in line behind the brake actuator is not fulling releasing. As in the wheel will drag. If I lift the wheel off the ground and give it a spin there is significant drag when compared to the other wheel with brake caliper. When spinning the wheel while off of the ground I can also hear the caliper dragging on the rotor.

This weekend I blocked the wheels of the trailer and with my tow vehicle applied and released the surge brakes. This is what I have so far:

• The first brake caliper in line behind the brake actuator will apply the brakes but will not fully release
• The dragging I feel on the first brake caliper is consistent. It doesn't feel as though the rotor is warped
• The second brake will apply the brakes and will fully release. No issues here.
• Also, both brake calipers have been replaced with brand new ones and there is no change

So it looks like the brake actuator is working properly. I wouldn't say there is air in the system since the second brake caliper is working properly. With both brake calipers already replaced I don't believe the issue is with the brake caliper.

I'm not sure what to look at next. The only thing I can think of is the brake rotor itself?

Any ideas on what I can check next?

[JCP]

Crack the brake line fitting open at the caliper. If it still drags, it's the caliper.