Whirlpool DWF 405 – LED flashing and motor going on and off

I have a Whirlpool DWF 405 which have been acting weird for a while now. In the very beginning of and a few times in the middle of a program, the washing machine alternately starts running and stopping (you hear the motor going on/off), between 50-100 times in a row. Simultaneously the LED goes on/off. It’s on for 1-2 seconds than it’s off for 1-2 seconds…

Sometimes the dishes aren’t clean in the end and there’s still some washing powder left, but most of the time the program still completes with good results. It sounds like this on/off thing is only happening when the machine is trying to drain itself. But there’s never any water left in the bottom at the end of a program.

I clean the filters I can see in the bottom of the machine regularly.

Anyone got an idea what’s wrong? Thank you.