I'm trying to bake out the front column after inlet maintenance but the pressure of the back inlet cannot reach the set point and continues to shutdown, also resulting in a shutdown of the front inlet. I've tried manually changing the back inlet pressure set point (i.e., set point was 23 but pressure wouldn't go above 22.3 psi; if I then change the set point to 20, the pressure cannot achieve that set point either). Any suggestions? My front column is a DB5-MS UI and the back column is DB-Select 624 UI, with attempting to bake out the front inlet at 250 degrees Celsius.