Huge Leak

My Truspec Micro CHNS analyzer will not pass the leak check. It wont hold pressure long enough to make it through the Step 1 stabilization stage. Then a message pops up that says huge leak. Ive changed the orings around boths sides of the combustion tube, the TC scrubber tube, anhydrone tube, helium scrubber tube, and reduction tube. Ive replaced all 7 orings behind the TC cell and behind all of the IR cells. Everything on the ambient monitor page is withing range, all cell voltages look good and it will pass the system check. Whenever I put the metal plate on the loading head interface instead of having the loading head attached it still fails the leak check. Does anyone know anywhere else in the system I should check or has anyone experienced this before? Thank you!!