What i know is when u driving using foot brake, is normal, bcos it use the brake fluid to pump the caliber piston pushing the brake pad to grab the disc, If u using handbrake, it only using the internal stainless steel line to pull the trigger gear at the back for the rear disc, cable housing is the one to hold and protect the internal line and also handbrake pulling level strength.
If the spring housing for the brake cable is bended and crack , the internal stainless steel line is doing jobless. I facing this before and then change it. Now good and brake as normal. Thumb up~~~