An often overlooked culprit when a caliper seems to be sticking is the rubber flex line between the vehicle's axle brake line and the caliper. The rubber lines often appear perfect on the outside but have deteriorated and the inside is swollen, which allows the fluid to push the caliper piston out due to the high pressure, but won't allow the fluid to freely return to the lines/master cylinder and relieve the pressure, which causes the caliper to stick. The caliper may be fine, but appears to be sticking simply because the flexline won't allow the fluid pressure to release. The scenario causes the stuck caliper, overheated brake pads and caliper, excessive wear on one side of the axle compared to the other, etc.