My mother-in-law has been having issues with her front passenger side brakes. I replaced the front brakepads and rotors along with the front passenger side caliper and flushed the brake fluid when she was driving caliper piston on rotor (she drove so long with the brakes grinding that somehow the brake pad fell out). That was back in November of 2022. 

 Today she reported grinding again from the front passenger side wheel. I inspected the front driver side brakes and found they had plenty of material left on the pad. The front passenger side was metal on metal (this time brake pad metal to rotor).

I'm planning on replacing the caliper again and doing another flush but is there anything else I should check? One of the slide pins on the caliper I'm planning on replacing doesn't slide as smooth as I would like, especially since it's only 8 months old but I'm not sure if this is the entire cause for her issues. The brake hose looks fine and not kinked. I can't think of anything else that might cause this.