I've always loved the looks of knuckle couplers so when I built my little 4 x 8 layout. Pics at The Train Guy I decided to remove all horn hook couplers and make the switch. Everything looks great and runs fairly well, but there's a 4% grade and at the top of the grade, the height difference between the car that's at the higher level, and the car coming up the grade causes one coupler to raise above the other and decouple the cars. Then the entire train comes back down the mountain. Any ideas on how to solve this? Shims in the couplers, etc.? The layout runs great with my old equipment and horn hook couplers but every proto2000 piece I put on it comes disconnected.:curse: