Dough, you called it! For some reasom, I thought the calipers actually slide on the pins. Well, they don't! The caliper moves with the pin which slides inside of the caliper support (caliper bracket). My caliper supports were all gummed up. I could barely pull the sliding pins out of the caliper support! I am going to give your gun brush a try to clean them out. Probably didn't need these rebuilt calipers...the supports were causing the problems!