Your sheet er comes in 5 different models. SFS ____ . What is the power design of the machine and what is your measured input power. Has it been converted from 50 to 60 cycle?
9 errors are usually switching problems. Like a overload opening. Sometimes from overheat or loss or cooling to the control system. Like dirty heat sinks or fans. Airflow obstruction. Especially to the Inverters. There should be nothing stacked around or near the machine for this reason. Beyond that you’ll have to contact Rondo. It may need a software upgrade.
I’ve made a habit to check the internal fans on inverters. If they fail the inverter will over heat after some time of operation. Remove it and look through the top/bottom while in operation, or use a mirror and flash light.
I’ve never had to work on a 4000, but I do know that Rondo designs for all the dust and flour these machines see. Not certain of how they handle the cooling aspect of this. But I’m sure that they have done something special.