The cargo crane does not slew. Troubleshooting

Greetings! Today we have a problem with the cargo crane, it won’t slew. In this case, there are no signals or alarms, the crane starts up, executes the commands “jib up, hook up” and “jib down, hook down,” but does not slew in any direction.

According to the instructions for the crane, you need to check the following circuit: Joystick - PLC - relay - Proportional Driver Unit - Proportional Valve.

Let's check the entire electrical circuit and figure out the reason for the improper operation of the cargo crane.