1975 Duster, slant 6, auto, had factory installed disc brakes on front, drum on back. Last trip out on long cruise. After we had been driving for a while, over an hour, we noticed whenever I had to apply heavy pressure to the brakes, we heard a grinding noise. Light pressure on the brakes, we didn't notice the noise. After returning home, I pulled one wheel. The rotor surface is wearing unevenly, looks to have plenty of thickness still but but due to the unevenness of the wearing probably should be turned. I could not pull the caliper off, more to come about this. What I could see of the pads, they seemed like they have thickness still although I could not measure them to be sure. I removed the 2 bolts/brackets that hold the caliper in place but the pads are tight against the rotor surfaces. The pads being tight against the rotor is the reason I couldn't get the caliper off. So my question is, should these pads be this tight or should I be looking for a specific problem? Thanks in advance.