There is a small magnet 6mm dia inside the brew head (filter cup) which goes rusty and disintegrates.
Solution: buy a 6mm dia magnet no longer than 6mm (from amazon) and replace.
Repair procedure: Slide brew head from machine. On the bottom in the middle is a screw holding the drip lever, undo and take out the componant and the long thin arm has a magnet in it . Probably rotten remove with tweezers and insert new one. Maybe with a little bit of glue.
Reassemble.
Job done.