Pump gradient does not run and pump stuck in isocratic elution

You have done some great diagnostics, which appear to eliminate the flow selection as the cause. Unfortunately it looks like the gradient controller is not functioning? I am not familiar with the inner workings of your system, but as it is an older design it maybe easy to find out how the pump(s) are triggered - it depends if it is a single pump with proportioning valve or a two pump system. It may require a signal to start the gradient function, You can check the closures on the back. And if there is a manual override in the software to start the gradient? ( I guess you already looked there?). Maybe a quick call to the manufacturer may get you some free diagnostic advice? Good luck.

Breeze has single pump with gradient proportionating valve.  The simple method is to choose individually A OR B OR C OR D for flow. If all the poarts are working, then it will work in gradient mode. Here you can find out which port of your GPV is faulty. Once that is located, either you cdan get the GPV replaced or if you are working in binary mode, avoid that particular faulty Port of GPV and choose other working combinaton for gradient.

The system has two pumps not one.  Where I work we are looking into this because we recently started working with a Breeze 2 software , binary pump system 1525 , and 2489 detector.  If we have any sucess resolving this i will try to let you know.