Disc Brake Conversion-Complete

I bought a complete Titan kit for my two axle trailer, it locks up great when I pull the emergency safety brake. 3 out the 4 tires spin freely when the brake is off but one if very stiff, i can turn it with two hands and lots of force. I pulled everything apart and it floats well on the two studs, no binding. I pulled the caliper off and pulled the emergency brake to make the piston come out 1/2", then I used a c-clamp to push it back in, it was super tight. It is brand new so no rust, no marks, nothing visible to keep it from moving easily. When I reassembled it improved to my two handed turn, before this it was extremely hard to move. It is still harder to move than the others. I took it on a mile test drive and 3 discs were 130* and the 4th was 170*, so obviously I still have a problem. I have contacted the store I bought it at and requested a replacement caliper. Just thought I would check here if there is something I overlooked.

Thanks

Leon