I recently purchased a used Spectrum F40PH (older Version). When I checked the front coupler height, I found it to low and it would catch on the  ties when run forward. I switched out the Kadee coupler for an EZ mate off set shank coupler. The height was better but when run forward the centering pin still caught the ties. after a closer look, I found that the coupler pocket sagging at a downward angle. Any thoughts on how to solve this problem?