Strange sound

This is Eildert, looking at the debris screen filter "A" in the sea-coolingwatersystem of unit EC20.
A strange sound is coming out of it as the screens pass by, so we had to investigate.
We opened the covers of the casing and stopped the pump which supplies the spraywater to clean the screens from fish, crabs, shrimps, seaweed and so on.
The spraywater sprays everything from the screen into a gutter which leads it back to the sea.
These screens are mounted on a kind of ladder, which is slowly turning.
From here it goes about 10 meters down and below sealevel.
We could not find anything broken but the howling sound didn't stop.
The only thing we could do was to close the hatches and make an order for the maintenance department to take a look as soon as possible.

Notice the big emergency pushbuttons left and right, each filter is supplied with one.