Sounds like a rebuild with used seals! These engines are very touchy when disassemble and assembling If the rebuild has brand "NEW" housings the car will never show 60 psi unless the apex seal were reused.The only time you can reuse Apex seals is if they come from the original housing. So say you have a 12a never open, when you take that engine apart the three apex seals go with the original housings it comes from. Rotors are not supposesd to be interchanged from front to back cause then balance of the engine will be gone! Rotors rarely go bad usually when you break apex seals or Rotor bearings go out thats when Rotors can get damaged.....