Mechanical timer program selector stops ⇐ Bosch

[Alexander 34]

Good afternoon!
Old BOCH dishwasher, with mechanical control. She is approximately 17 years old. Apart from a couple of small repairs, it works “like a clock.”
And now the situation: I put it into operation, it works for a while and this timer/selector stops in one place. The machine seems to be working, but the timer is on. If you move it a little, the program moves on and everything ends well. Tell me, can this be fixed, or is this selector likely to be replaced?

[Boil]

Maybe try cleaning it? Dust, dirt, grease?